Salts and ionic liquids of resonance stabilized amides

Article abstract of DOI:10.1002/asia.200900181

The synthesis, structure, and bonding of alkali salts of resonance stabilized amides, such as diformylamide (dfa), formylcyanoamide (fca), nitrocyanoamide (nca), and for comparision, the well-known dicyanoamide (dca), are discussed on the basis of experim

Full text of DOI:10.1002/asia.200900181

FULL PAPERS
DOI: 10.1002/asia.200900181
Salts and Ionic Liquids of Resonance Stabilized Amides
Harald Brand,[a] Jçrn Martens,[a] Peter Mayer,[a] Axel Schulz,*[b, c] Markus Seibald,[a] and
Thomas Soller[a]
Abstract: The synthesis, structure, and
bonding of alkali salts of resonance sta-
bilized amides, such as diformylamide
(dfa), formylcyanoamide (fca), nitro-
cyanoamide (nca), and for comparision,
the well-known dicyanoamide (dca),
are discussed on the basis of experi-
mental and theoretical data. The first
structural reports of K(18-crown-6)+
dfaꢀ, K(18-crown-6)+fcaꢀ, Na+ncaꢀ,
network-like structures in the solid
state. For comparison, the X-ray struc-
tures of covalently bound phenyldicya-
noamide and diformamide are also dis-
cussed. The thermal behavior of the
alkali salts of these amides is studied
have been prepared and were fully
characterized, namely the dfa, fca, and
nca salts of EMIM (1-ethyl-3-methyl-
imidazolium),
BMIM
(1-butyl-3-
methyl-imidazolium), and HMIM (1-
hexyl-3-methyl-imidazolium). Most of
them are liquid at room temperature,
except BMIM+fcaꢀ that melts at 328C.
These ionic liquids are neither heat nor
shock sensitive, are thermally stable up
to over 2008C, and can be prepared
easily in large quantities.
by
thermoanalytical
experiments.
Moreover, several novel ionic liquids
based on resonance stabilized amides
and LiACHTUNGTRENNUNG
(TMEDA)+dcaꢀ are presented.
Keywords: amides · density func-
tional calculations · ionic liquids ·
halides · Raman spectroscopy
Examination of the X-ray data reveals
almost planar anions with strong
cation–anion interactions resulting in
Introduction
The first alkali diformylamide compound was reported by
Allenstein and Beyl in 1967.[3] In contrast to the experimen-
tally unknown acid of dca, HN(CN)2, the free acid of dfa,
Amides of the type [NR1R2]ꢀ with R1,2 =CHO, NO2, CN,
being an electron withdrawing group, can be regarded as
nonlinear resonance stabilized pseudohalides.[1] Although
salts of dicyanoamides are well-studied, much less is known
about formylamide, formylcyanoamide, and nitrocyanoa-
mide salts.[2]
HNACTHUNTRGENNG(U CHO)2, has been synthesized and identified on the
1
basis of IR, microwave, and H NMR data.[3–5] As expected
for a pseudohalide, the silver salt is insoluble in water,[6] and
it was possible to isolate the very labile halogen–pseudohal-
ogen compound bromodiformylamide, BrNACTHNURTGNENG(U CHO)2, in small
yields.[3] Tetraformylhydrazine represents, according to the
pseudohalogen concept, a bimolecular pseudohalogen which
is known and fully characterized.[7] Sodium diformylamide is
easily prepared by treatment of sodium methanolate with
formamide at elevated temperatures [Eq. (1)]:[8]
[a] Dr. H. Brand, J. Martens, Dr. P. Mayer, M. Seibald, T. Soller
Department Chemie und Biochemie
Ludwig-Maximilians-Universitꢀt Mꢁnchen
Butenandtstr. 5–13, 81377 Mꢁnchen (Germany)
[b] Prof. Dr. A. Schulz
Universitꢀt Rostock
Institut fꢁr Chemie
Abteilung Anorganische Chemie
Albert-Einstein-Str. 3a, 18059 Rostock (Germany)
Fax : (+49) 381-498-6382
NaOCH3þ2 H2NCHO ! Na½NðCHOÞ2ꢁþNH3þH3COH
ð1Þ
Sodium formylcyanoamide has been synthesized from
sodium hydrogencyanoamide and ethyl formate according
to Equation (2).[9] However, detailed spectroscopic data of
alkali formylcyanoamides is still required.
E-mail: Axel.Schulz@uni-rostock.de
[c] Prof. Dr. A. Schulz
Leibniz-Institut fꢁr Katalyse e.V. an der Universitꢀt Rostock
Albert-Einstein-Str. 29a, 18059 Rostock (Germany)
Fax : (+49) 381-498-6382
Na½HNCNꢁþH5C2OCHO ! Na½NðCHOÞCNꢁþH5C2OH
ð2Þ
E-mail: Axel.Schulz@catalysis.de
Supporting information for this article is available on the WWW
under http://dx.doi.org/10.1002/asia.200900181.
1588
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Chem. Asian J. 2009, 4, 1588 – 1603

Besides the application of sodium and potassium formyl-
cyanoamide as precursors in heterocycle synthesis,[10] as well
as in some theoretical works on the free formylcyanoa-
mide,[11] inorganic covalently bound formylcyanoamides
have not yet been discussed in detail. However, the 3,4-di-
chlorophenyl[12] and the methylformylcyanoamide can be
found in the literature.[13]
in good yields.[3] For practical reasons we have passed HCl
gas directly into a stirred suspension of sodium diformyla-
mide [Eq. (4)].
Na½NðCHOÞ2ꢁþHCl ðgÞ ! HNðCHOÞ2þNaCl
ð4Þ
1
The H NMR spectrum of Hdfa shows two resonances in
the typical range of dicarbon acid imides (11.16 ppm, cf.
11.40 ppm for phthalimide H4C6(CO)2NH)[38] and forma-
mides (8.83 ppm, cf. 8.00 ppm for (Z)-N-methylformamide
(Z)-MeN(H)CHO), respectively.[39] As expected, a singlet is
found in the 13C NMR spectrum (167.2 ppm, cf. 163.6 ppm
for H2NCHO)[39] and 14N NMR spectrum (ꢀ207 ppm, cf.
ꢀ199 ppm for succinimide (H2C)2(CO)2NH).[40] On the basis
Analogous to the formylcyanoamides, alkali dicyanoa-
mides are also nonlinear pseudohalides with one lone pair
of the central nitrogen atom strongly delocalized into the
ꢀ
two p*ACHTUNGTRENNUNG(C N) bonds. Sodium dicyanoamide has been synthe-
sized as early as 1922 by Madelung and Kern.[14] Typically
for a pseudohalide, the heavy metal salts (Ag+, Hg22+, Pb2+
) are sparingly soluble in water.[14–16] Neither the free acid
nor any halogen–pseudohalogen species has been isolated so
far. Interestingly, Madelung and Kern have already observed
the trimerization of sodium dicyanoamide at “dark red
heat”.[17a] In the last decade, this trimerization process lead-
ing to promising melaminate salts has been the object of
great interest by several groups.[17,18] In addition, the synthe-
sis and structural investigations of a series of hitherto un-
known dca salts (earth alkali,[19] ammonium,[20] guanidini-
um,[21] rare earth,[22] and guanylurea[23]) have been reported
recently.
of B3LYP/6-31GACHTUNTRGNEUNG(d,p) computations, the experimentally ob-
tained vibrational frequencies of Hdfa were assigned to the
corresponding vibrations (Table 1).
Hdfa is hygroscopic and should be kept in a dry argon at-
mosphere. DSC studies revealed a melting point of 448C (cf.
428C)[3] and a boiling point of 1988C at atmospheric pres-
sure (cf. 1198C at 12 Torr [16 mbar]),[3] indicating an aston-
ishing thermal stability in contrast to the other free acids of
nonlinear pseudohalides.[1]
Three conformers (E,E; Z,E; and Z,Z) of Hdca have
been found at the potential energy surface (Figure 1), with
the E,E-conformer being the most stable isomer followed by
the Z,E-isomer (+0.2 kcalmolꢀ1) and the Z,Z-conformer
(+6.0 kcalmolꢀ1). Obviously, this trend can be attributed to
the decreasing number of formal intramolecular hydrogen
bonds (E,E: 2; Z,E: 1; and Z,Z: 0 hydrogen bonds). A
better explanation might be the
McKay and co-workers were the first group able to isolate
the explosive potassium nitrocyanoamide as they studied the
properties of N-alkyl-N-nitroso-N’-nitroguanidines.[24] For in-
stance, treatment of N-methyl-N-nitroso-N’-nitroguanidine
with MOH (M=alkali metal) yields, beside diazomethane,
the alkali nitrocyanoamide M[NACHTUNGTRNEUNG
(NO2)CN] [Eq. (3)].[25]
fact that E,E-conformer of
Hdfa avoids the destabilizing
1,3-interactions in contrast to
the E,Z and Z,Z form. This
finding is in contradiction to a
microwave study by Steinmetz
Another synthetic route starts from S-methyl-N-nitroiso-
(in 1973) who concluded from the experimental data that
the (Z,E)-diformamide should be favored energetically.[4]
Two years later, Noe and Raban reported (E,E)-diforma-
thiourea,[26] which can be converted to M[N
ACTHNUTRGENUGN(NO2)CN] in
basic solutions of MOH.[27] Nitrocyanoamide salts have been
studied as potential primary explosives.[28]
mide on the basis of H NMR data as the most stable con-
1
Since ionic liquids are increasingly receiving more atten-
tion owing to their wide spectrum of applications (as reac-
tion media, as lubricants, or as electrolytes particularly for
solar and fuel cells),[29–37] the EMIM (1-ethyl-3-methyl-imi-
dazolium), BMIM (1-butyl-3-methyl-imidazolium), and
HMIM (1-hexyl-3-methyl-imidazolium) salts of dfa, fca, and
nca have also been prepared and fully characterized.
former.[5] To shed some light on this structural problem, a
single crystal X-ray study was carried out.
X-ray Study of Hdfa
Single crystals of Hdfa suitable for X-ray structure analysis
were obtained from recrystallization in diethyl ether. Hdfa
crystallizes in the orthorhombic space group Pca21 with four
molecules per unit (Table 2). In agreement with the comput-
ed results the Hdfa molecule exhibits an (E,E)-conforma-
tion (Figure 1 and 2). The O1-C1-N1-C2 and C1-N1-C2-O2
dihedral angles amount to 179.48 and ꢀ179.48, respectively.
Thus the Hdfa molecule can be regarded as a planar C2v
symmetric species. Selected structural data are listed in
Figure 2. The computed and experimentally observed data
are in good agreement (for comparison see Table S1 in the
Supporting Information). The O1–C1 and O2–C2 distances
Results and Discussion
Synthesis, Properties, and Structure of Diformamide,
HNACTHNUTRGENUG(N CHO)2
According to Allenstein and Beyl, the addition of HCl gas
dissolved in diethyl ether to a suspension of sodium difor-
mylamide in diethyl ether at 08C gives HNACTHNURGTNEUNG(CHO)2 (Hdfa)
Chem. Asian J. 2009, 4, 1588 – 1603
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1589

A. Schulz et al.
FULL PAPERS
Table 1. Calculated and experimental vibrational data of Hdfa (cmꢀ1
along with an approximate assignement.[a]
)
assignment[b]
B3LYP/6-31GAHCTUNGTRENNUNG
IR[e]
nNꢀ
ns,C
ꢀ
3584
3002
2982
1858
1825
1478
1450
1348
1256
1185
1044
1031
N
3256(1)
2955(2)
2934(1)
1739/1719(10)
–
3262s
H
2917m
2898sh
1745s
1686vs
1480m
1412w
H
nas,C
ꢀ
H
ns,C
=
O
nas,C
=
O
das,N
H (ds,C )
ꢀ
H
1450(1)
1431(5)
ꢀ
ꢀ
H/C
Figure 2. ORTEP drawing of the molecular structure of Hdfa in the crys-
tal. Thermal ellipsoids with 50% probability at 200 K. Selected bond
das,C
ꢀ
H
ds,N
H (ds,C )
ꢀ
H
1372/1359
1264(1)
ACHTUNGTREN(NGNU 0.4) 1373/1347m
ꢀ
ꢀ
H/C
ꢀ
ꢀ
ꢀ
lengths [ꢃ] and angles [8]: O1 C1 1.206(3), N C2 1.356(3), O2 C2
ns,C
ꢀ
nas,C
1264m
N
ꢀ
1.209(2), N C1 1.374(3); C1-N-C2 122.5(2), O1-C1-N 124.0(2), O2-C2-
1192/1167
ACHTUNGTRENNUNG
ꢀ
N
H3 121.1(16), C1-N-H3 117.0(20), O2-C2-N 124.6(2), N-C1-H2 112.6(14),
C2-N-H3 120.0(20), O1-C1-H2 123.2(14), N-C2-H3 114.1(16).
gs,C
ꢀ
gas,C
1090/1077ACTHUNGTRENNUNG
H
1038
A
–
ꢀ
H
gNꢀ
das,NCO
742
629
533
N
769
–
547(9)
231(1)
R
796m
649s
527m
–
H
ds,NCO
lengths of 1.374 ꢃ and 1.356 ꢃ correspond to a partial
dOHC-N(H)-CHO,bending 248ACHTUNGTRENNUNG
ꢀ
double bond character (cf. d
N
(C N)=
[a] Data correspond to the (E,E)-conformer of Hdfa. [b] s=symmetric
and as=antisymmetric mode. [c] Unscaled calculated frequencies; in
round brackets: IR intensities (kmmolꢀ1), Raman activities (ꢃ4 amuꢀ1).
[d] Experimental Raman intensity scaled to the maximum value 10.
[e] KBr pellet.
A number of inter- and intramolecular hydrogen bonds
ranging from 2.2 to 2.9 ꢃ are observed (Figure 3). More-
over, the hdfa molecules are arranged in two planes, which
are almost perpendicular to each other. The very good ther-
mal stability can be attributed directly to the large number
of strong hydrogen bonds.
The electronic structure is best represented by the reso-
nance between the three Lewis structures shown in Figure 4,
indicating a partial CN double bond through the delocaliza-
tion of the nitrogen lone pair into CO p* orbitals.
Figure 1. Computed conformers of Hdfa.
are 1.206 ꢃ and 1.209 ꢃ, respectively, in accord with the cal-
culated value of 1.209 ꢃ. The N1 C1 and the N1 C2 bond
ꢀ
ꢀ
Synthesis, Properties, and
Structure of Alkali
Diformylamides, M[NACHTUNGTRENNUNG(CHO)2]
Table 2. Crystallographic data.[a]
Hdfa
K(18-crown-6)+dfaꢀ
K(18-crown-6)+fcaꢀ
Phdca
Na+ncaꢀ
formula
M
crystal system
space group
a [ꢃ]
b [ꢃ]
c [ꢃ]
a [8]
C2H3NO2
73.05
orthorhombic
Pca21
8.0885(3)
4.7789(2)
8.2554(3)
90
C14H26KNO8
375.46
orthorhombic
P212121
8.190(7)
10.764(5)
21.173(8)
90
C14H25KN2O7
372.46
monoclinic
Pc
8.2266(13)
14.314(2)
8.1294(14)
90.00
99.629(14)
90.00
943.8(3)
2
1.311
0.316
0.71073
295
3200
C8H5N3
143.15
monoclinic
P21/c
7.4864(7)
6.0980(4)
15.5461(16)
90.00
94.556(4)
90.00
707.47(11)
4
1.344
0.087
0.71073
200
2481
1379
0.092
680
296
0.0545
0.1153
0.90
CN3NaO2
109.02
monoclinic
P21/n
3.5888(4)
15.414(2)
6.7803(7)
90.00
101.035(13)
90.00
368.14(8)
4
1.967
0.273
0.71073
200
3164
828
0.032
683
216
0.0250
0.0685
1.03
Alkali diformylamides are
easily prepared in an acid/base
reaction of Hdfa and MOR
(M=alkali metal, R=Me, tBu,
and so forth) in THF at 08C.[3]
The 1H NMR spectrum shows
one resonance at 8.95 ppm
which lies in the typical range
of formamides (cf. 8.00 ppm
b [8]
90
90
90
g [8]
90
V [ꢃ3]
Z
319.11(2)
4
1.521
0.137
0.71073
200
1866.6(19)
4
1.336
0.323
0.71073
295
3400
2921
0.0339
2465
800
1calcd. [gcmꢀ3
]
for
(Z)-N-methylformamide
m [mmꢀ1
]
(Z)-MeN(H)CHO).[39] Only a
singlet resonance is found in
the 13C NMR (181.3 ppm, cf.
lMoKa [ꢃ]
T [K]
measured refl.
indep. refl.
Rint
8495
736
0.055
598
178.6 ppm
anion (H3CCO)2Nꢀ)[42] and
14N NMR
spectrum
(ꢀ128 ppm, cf. ꢀ140 ppm for
in
diacetamide
2955
0.0108
2270
obs. refl.
F
G
152
396
R1
wR2
GooF
0.0378
0.1038
1.11
0.0368
0.0878
1.07
0.0442
0.1075
1.11
sodium
succinimide
(H2C)2(CO)2NNa).[43] IR and
Raman data are listed in
Table 3.
# of parameters
59
217
217
120
64
[a] dfa=diformylamide, fca=formylcyanoamide, dca=dicyanoamide, nca=nitrocyanoamide.
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Salts and Ionic Liquids of Resonance Stabilized Amides
Computations at the B3LYP/6-31GACTHNUTRGNEUNG(d,p) level of theory
resulted in three possible conformers for the dfa anion
(Figure 5) which are all close in energy. The planar C2v sym-
metric (E,E)-conformer is energetically favored and stabi-
Figure 5. Computed isomers of the dfa anion.
Figure 3. Inter- and intramolecular hydrogen bonds in Hdfa (distances in
ꢃ).
lized by 2 kcalmolꢀ1 compared to the non-planar C1 sym-
metric (Z,E)-conformer, as well as 7 kcalmolꢀ1 with respect
to the C2 symmetric (Z,Z)-conformer. In the (E,E)-diformy-
lamide anion, the lone pair density localized at the central
nitrogen atom is best delocalized according to Figure 6.
X-ray Study of [K(18-crown-6)][NACTHNURGTNEUNG(CHO)2]
To the best of our knowledge, no X-ray data of any diformy-
lamide salts have been published yet. Since we did not suc-
ceed in obtaining single crystals
Figure 4. Lewis structures of Hdfa.
of K+dfaꢀ, the compound was
Table 3. Experimental and theoretical IR and Raman data (cmꢀ1) of dfa salts along with an approximate assi-
gment.[a]
recrystallized in the presence of
18-crown-6 ether in THF.
[K(18-crown-6)]ACTHNUTRGNEUGN[dfa] crystalli-
B3LYP/
6-31G
(d,p)[c]
Li+dfaꢀ
Na+dfaꢀ
Raman[d]
K+dfaꢀ
assignment[b]
ns,C
AHCTUNGTRENNUNG
Raman[d]
IR[e]
IR[e]
Raman[d]
IR[e]
zes in the orthorhombic space
group P212121 with four formula
units per cell (Table 2). Each
asymmetric unit consists of
2693
2633
1794
1707
1463
1441
1327
1246
1056
A
2847(1)
2766(2)
1747/1709(10)
–
2856w
2747vw
1694vs
1604vs
1386s
1370s
1287m
1263m
1055w
785m
618m
–
2862(2)
2776(2)
1677(10)
–
1422(3)
1405(1)
1274(1)
1261(2)
1063(1)
–
2833m
2716w
1694s
1591vs
1388m
1363s
1291m
1264m
1089w
778m
605m
–
2853(1)
2771(2)
1668(10)
–
1421(3)
1409(1)
1294(1)
1258(2)
1051(1)
–
2838w
2771w
1698s
1560vs
1387m
1349m
1282s
1251m
1130w
740m
610m
–
ꢀ
H
nas,C
ACHTUNGTRENNUNG
ꢀ
H
ns,C
ACHTUNGTRENNUNG
=
O
nas,C
ACHTUNGTRENNUNG
=
O
das,C
R
–
K+(18-
ꢀ
H
single
independent
ds,C
ꢀ
H
R
1415(2)
1313/1308(1)
1268(1)
1048(1)
–
crown-6) and dfa components
with two strong cation···anion
nas,C
ACHTUNGTRENNUNG
ꢀ
N
ns,C
ꢀ
N
ACHTUNGTRENNUNG
gs,C
ꢀ
H
ACHTUNGTRENNUNG
ꢀ
contacts (d
G
das,NCO
743
591
312
ACHTUNGTRENNUNG
ꢀ
G
ds,NCO
A
616(4)
339(1)
602(8)
320(2)
593(8)
317(2)
However, there are no bridging
interactions of the dfa anions,
hence no coordination polymer
was found.
dOHC-N-CHO,bending
ACHTUNGTRENNUNG
[a] Data correspond to the (E,E)-conformer of dfa anion. [b] s=symmetric and as=antisymmetric mode.
[c] Unscaled calculated frequencies; in round brackets: IR intensities (kmmolꢀ1), Raman activities (ꢃ4 amuꢀ1).
[d] Experimental Raman intensity scaled to the maximum value 10. [e] KBr pellet.
In agreement with our com-
putation (Table S2 in Support-
Alkali diformylamides should be stored under dry nitro-
gen/argon atmosphere. They are moisture sensitive and de-
compose rapidly in the presence of water according to
Equation (5) (M=alkali metal):
M½NðCHOÞ2ꢁþH2O ! M½HCO2ꢁþH2NCHO
ð5Þ
Figure 6. Lewis representations of the (E,E)-diformylamide anion.
DSC experiments on alkali diformylamides of the type
(M[N
(CHO)2], M=Li, Na, K) showed that Li+dfaꢀ should
G
ing Information) the anion adopts a (E,E)-conformation
with an almost planar C2v symmetric dfa anion (dihedral
angles: O1-C1-N1-C2 179.18 and C1-N1-C2-O2 179.08,
possess the lowest melting point. However, Li+dfaꢀ decom-
poses at 1758C (decomposition onset) in an exothermic re-
action before reaching the expected melting point. The
melting point of Na+dfaꢀ was observed at 2428C, further
heating leads to decomposition at 2868C. A similar result
was found for K+dfaꢀ (m.p. 2378C, Tdec above 3848C).
ꢀ
ꢀ
Figure 7). The O1 C1 and O2 C2 bond lengths amount to
1.227 and 1.193 ꢃ, respectively, which is in the range expect-
ed for a C=O double bond (cf. d
bond lengths of 1.319 ꢃ and 1.339 ꢃ for the N1 C1 and
(C=O)=1.230 ꢃ).[41] The
covACHTGNUTRENNUNG
ꢀ
Chem. Asian J. 2009, 4, 1588 – 1603
ꢂ 2009 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.chemasianj.org
1591

A. Schulz et al.
FULL PAPERS
and (7)]. The hitherto unknown silver salt was obtained by
salt metathesis reaction according to Equations (8) and (9).
NaOCH3þH2NCN ! Na½HNCNꢁþHOCH3
ð6Þ
Na½HNCNꢁþH5C2OCHO ! Na½NðCHOÞCNꢁþHOC2H5
ð7Þ
ð8Þ
AgNO3 ðaqÞþNa½NðCHOÞCNꢁ ðaqÞ !
Ag½NðCHOÞCNꢁ # þNaNO3 ðaqÞ
M½NðCHOÞCNꢁþH2O ! M½HCO2ꢁþH2NCN
ð9Þ
Alkali formylcyanoamide (fca) salts are moisture sensitive
and decompose slowly to alkali formates in the presence of
traces of water [Eq. (9)] as shown by 13C NMR studies. The
almost water-insoluble silver formylcyanoamide is very sen-
sitive to light and heat. It decomposes within 3 h in daylight
and even in the dark at ambient temperature after 24 h.
Salts of formylcyanoamide are easily characterized by 1H,
13C, and 14N NMR spectroscopy (1H NMR: 8.49 ppm, cf.
Figure 7. ORTEP drawing of the molecular structure of K(18-crown-6)+
[N
295 K. Hydrogen atoms of the crown ether are omitted for clarity. Select-
ACHTUNGTRENNUNG
(CHO)2]ꢀ in the crystal. Thermal ellipsoids with 50% probability at
ꢀ
ꢀ
ꢀ
ed bond lengths [ꢃ] and angles [8]: O1 C1 1.227(4), N1 C1 1.319(4), K
ꢀ
ꢀ
ꢀ
O1 2.779(3), O2 C2 1.193(5), N1 C2 1.339(5), K N1 3.020(3); C1-N1-C2
114.0(3), N1-C2-O2 126.8(5), K-O1-C1 99.3(2), N1-C1-O1 124.9(3), N1K-
O 145.60(8), K-N1-C1 86.2(2).
8.00 ppm
CHO);[39] 13C NMR: 172.9 and 123.4 ppm, cf. 165.4 ppm for
(E)-N-methylformamide and
(E)-MeN(H)CHO)[39]
128.7 ppm benzoylcyanoamide
PhC(O)N(H)CN);[45]
for
(Z)-N-methylformamide
(Z)-MeN(H)-
ꢀ
N1 C2 bonds lie in the range between a CN double and
[41]
ꢀ
single bond (d
(C=N)=1.270; d
N
N1-C1-O1 angle of 124.98 and 126.88 for the N1-C2-O2
angle correspond to formal sp2 hybridized nitrogen. Com-
pared to the free acid Hdfa, the C-N-C angle decreases
from 122.5 to 114.08, which can be explained on the basis of
the VSEPR model,[44] requiring larger space for the lone
pairs in the anion.
14N NMR: ꢀ190 and ꢀ245 ppm cf. ꢀ184 ppm for H2NCN[46]
and ꢀ268 ppm for HC(O)15NH2).[47] Experimentally ob-
served IR and Raman data of several formylcyanoamide
salts are listed in Table 4 together with computed vibrational
data which have been used for an approximate assignment.
DSC experiments revealed no melting point for the lithium
salt since exothermic decomposition starts at 1948C, while
Na+fcaꢀ melts at 2538C and decomposes above 3018C. Sim-
Synthesis, Properties, and Structure of Alkali and Silver
ilar findings are obtained for K+fcaꢀ (m.p. 1828C, Tdec
2598C).
=
Formylcyanoamides, M[NACTHUNTGRENNG(U CHO)CN]
In a modified literature synthesis,[9] formylcyanoamide salts
were prepared in a two step procedure: First, the alkali
methoxide was treated with cyanoamide to give the corre-
sponding alkali cyanoamide salt in situ. Finally, addition of
ethyl formate yields the alkali formylcyanoamide [Eq. (6)
Computations showed two isomers (Figure 8) with the
(E)-conformer slightly favored over the (Z)-conformer by
1 kcalmolꢀ1. Selected structural data of both isomers can be
found in Table S3 in the Supporting Information. The elec-
tronic structure is best explained by resonance between the
Table 4. Computed and experimental vibrational data of fca salts (cmꢀ1) along with an approximate assignment.[a]
assignment
B3LYP/
6-31G
(d,p)[b]
Li+fcaꢀ
Na+fcaꢀ
Raman[c]
K+fcaꢀ
Ag+fcaꢀ
Raman[c]
G
Raman[c]
IR[d]
IR[d]
Raman[c]
IR[d]
IR[d]
nCꢀ
2762 (101,235)
2252 (102,391
1748 (4,782)
1442 (11,6)
1358 (10,157)
1094 (5,59)
1039 (3,4)
638 (8,4)
607 (4,3)
578 (2,9)
200 (6,8)
191 (1,18)
2910 (2)
2210 (10)
1594/1573 (2)
1384 (3)
1328 (9)
1006 (2)
864 (3)
617 (1)
604 (1)
543 (1)
262 (9)
2896w
2202s
1589vs
1388m
1334s
1090w
1001w
640w
600m
540m
–
2882 (3)
2180 (10)
1578 (4)
1383 (3)
1329/1300 (4)
984 (3)
843 (3)
613 (1)
–
2882w
2207s
1597vs
1384m
1320s
1086m
963w
638w
608m
524m
–
2857 (3)
2178/2142 (9)
1606/1592 (2)
1402 m
1330/1306 (1)
1001 (1)
882 (1)
642 (10)
611 (1)
–
2857m
2196s
1622vs
1402m
1313s
1080s
930w
642m
592m
553w
–
2916 (2)
2181 (10)
1598 (2)
1390 (2)
1319 (1)
–
2894w
2184s
1614s
1396w
1292m
1084w
–
–
–
–
–
–
H
nCꢂN
nC
=
O
dCꢀ
nas,C
H
ꢀ
N
ns,C
ꢀ
N
gCꢀ
–
H
dNCN
dNCO
gNCN
634 (6)
607 (1)
556 (1)
236 (3)
–
522 (1)
216 (4)
132 (5)
dNC-N-CHO,bending
gNC-N-CHO,twist
230 (4)
140 (3)
158 (4)
–
–
–
[a] Data correspond to the (E)-conformer of fca anion. [b] Unscaled calculated frequencies; in round brackets: IR intensities (kmmolꢀ1), Raman activi-
ties (ꢃ4 amuꢀ1). [c] Experimental Raman intensity scaled to the maximum value 10. [d] KBr pellet. [e] ATR sensor.
1592
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Chem. Asian J. 2009, 4, 1588 – 1603

Salts and Ionic Liquids of Resonance Stabilized Amides
Figure 8. Computed conformers of the fca anion.
ACTHNUTRGNEUNG
Figure 11. Cation–anion interactions in K(18-crown-6)+[N(CHO)CN]ꢀ
resulting in the formation of chains throughout the unit cell. Hydrogen
atoms of the crown ether are omitted for clarity.
Lewis representations shown in Figure 9. While representa-
tion A describes a formylcarbodiimide, B corresponds to a
formylcyanoamide, and C can be classified as an iminolate.
According to NBO analysis[48–51] formylcyanoamide B seems
to possess the largest weight.
As predicted by theory, the anion was observed in the en-
ergetically favored (E)-conformation. In contrast to the
planar Cs symmetric anion computed for the gas phase, the
experimental data revealed a strong distortion from planari-
ty as displayed by the N-C-N-C torsion angle of 108.28. The
N1-C2-N2 angle with 161.98 is also much smaller than calcu-
lated for the gas phase ion, where a value of 174.98 was esti-
mated. These strong deviations may be attributed to the
Figure 9. Lewis representations of the (E)-formylcyanoamide anion.
ꢀ
considerable cation···anion contacts. The observed O1 C1
bond length is 1.174 ꢃ, which is in accordance with a C=O
double bond. The N–C distances amount to 1.151 along the
cyano group, and to 1.213 ꢃ and 1.275 ꢃ along the C-N-C
moiety, respectively.
X-ray Study of [K(18-crown-6)][NACTHNUTRGNE(NUG CHO)CN]
To the best of our knowledge, no X-ray data of any formyl-
cyanoamide salts is available. In analogy to K+dcaꢀ, no
single crystals of K+fcaꢀcould be obtained directly. Instead,
K+fcaꢀ was recrystallized in the presence of 18-crown-6
Synthesis, Properties, and Structure of
Phenylformylcyanoamide
ether in THF. [K(18-crown-6)]ACTHNUTRGENUGN[fca] crystallizes in the mono-
clinic space group Pc with two formula units per cell
The first synthesis of phenylformylcyanoamide was achieved
through the reaction of potassium phenylformylamide[52]
with one equivalent of cyanogen bromide in acetonitrile
(Scheme 1). Recrystallization from chloroform yields pure
phenylformylcyanoamide.
(Table 2). The asymmetric unit consists of the ion pair K(18-
ACHTUNGTRENNUNG
crown-6)+/[N(CHO)CN]ꢀ (Figure 10). Strong cation–anion
interactions lead to chains of alternating K(18-crown-6)+
and fca ions. Every fca ion forms a bridge between two cat-
ions, one interaction via the nitrogen atom of the cyano
group and one via the oxygen atom of the formyl group
(Figure 11).
Scheme 1. Synthesis of phenylformylcyanoamide.
Although phenylformylcyanoamide is neither hygroscopic
nor air sensitive, it should be stored under inert gas since it
slowly decomposes in the presence of moisture according to
Equation (10). The labile phenylcyanoamide reacts further
to give the trimer.[53]
PhNðCHOÞCNþH2O ! HCO2HþPhðHÞNCN
ð10Þ
Figure 10. ORTEP drawing of the molecular structure of K(18-crown-6)+
[N
295 K. Hydrogen atoms of the crown ether are omitted for clarity. Select-
ACHTUNGTRENNUNG
(CHO)CN]ꢀ in the crystal. Thermal ellipsoids with 30% probability at
Pure phenylformylcyanoamide melts at 558C and vaporiz-
es at temperatures above 1958C at standard pressure.
1H NMR spectroscopic studies revealed two resonances: A
singlet at 9.02 ppm (cf. 8.55 ppm for N,N-diphenylformamide
Ph2NCHO)[54] and a multiplet in the typical aryl range
ꢀ
ꢀ
ed bond lengths [ꢃ] and angles [8]: O1 C1 1.174(10), N1 C2 1.275(13),
ꢀ
ꢀ
ꢀ
ꢀ
K1 O1, 2.811(7), N1 C1 1.213(11), N2 C2 1.151(13), K N2 2.823(7);
C1-N1-C2 123.0, N1-C2-N2 161.9(9), N1-C1-O1 136.0(9), K1-O1-C1
113.4(6).
Chem. Asian J. 2009, 4, 1588 – 1603
ꢂ 2009 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.chemasianj.org
1593

A. Schulz et al.
FULL PAPERS
(7.50–7.18 ppm, cf. 7.58–6.99 ppm for N-phenylforma-
mide).[54] The 13C NMR spectrum shows a singlet resonance
in the expected range of formamides (163.5 ppm, cf.
165.4 ppm for (E)-N-methylformamide (E)-MeN(H)-
CHO),[39] four aryl resonances (130.7, 129.7, 129.4, and
127.3; cf. 140.9–124.0 N,N-diphenylformamide),[54] and a cya-
noamide resonance (116.3 ppm, cf. 111.2 ppm for N-phenyl-
cyanoamide PhN(H)CN).[55] Two singlets are found in the
14N NMR spectrum at ꢀ159 ppm (cf. ꢀ164 ppm for 2,6-di-
chlorphenyl-15N(H)C15N)[56] and at ꢀ203 ppm (cf. ꢀ207 ppm
for diformamide). Selected vibrational data are listed in
Table S4 in the Supporting Information.
tive partial charges (NPA charges: q(Nterminal)=ꢀ0.58/q-
G
(Ncentral)=ꢀ1.34 e). Accordingly, the HOMO possesses large
coefficients at the terminal nitrogen atoms (Figure 14).
Two isomers of phenylformylcyanoamide were found at
the B3LYP/6-31G
(d,p) level of theory (Figure 12). Both iso-
Figure 14. HOMO of the dca anion with B1 symmetry.
mers are separated by only 1 kcalmolꢀ1 and can be regarded
ꢀ
as conformers with respect to rotation about the N(CN)
CHO bond (Table S5 in the Supporting Information).
A good hint for the prefered reaction of the terminal ni-
trogen atoms during an electrophilic attack can be observed
experimentally when, for example, lithium dicyanoamide is
crystallized in the presence of TMEDA (N,N,N’,N’-tetrame-
thylethylendiamine, Figure 15). Chains of Li
dcaꢀ units are found with the dca anion bridging two Li-
(TMEDA)+ ions by means of the terminal nitrogen atoms.
(TMEDA)+
ACHTUNGTRENNUNG
AHCTUNGTRENNUNG
No contacts between the central amide nitrogen atom with
the cations can be found. The Li+ ion is bonded to each ni-
trogen atom of the TMEDA molecule and to one terminal
nitrogen atom of both bridging dca anions, thus forming a
tetrahedral coordination environment around the lithium
Figure 12. Computed isomers of phenylformylcyanoamide.
Some Aspects with Respect to Alkali Dicyanoamides,
M[N(CN)2], the Free Acid, HN(CN)2, and
Phenyldicyanoamide, Ph-N(CN)2
ꢀ
cation with Li N distances between 1.97–2.11 ꢃ.
Synthesis and properties of alkali dicyanoamides have been
studied intensively over the last decades.[10–23] We want to
focus here on covalently bound dicyanoamides, for which
little is known. Alkali dicyanoamides are stable in neutral
aqueous solution; however, they tend to polymerize at
lower pH values. Hence, all attempts to isolate the free acid
dicyanoamide, HN(CN)2 have failed. One of the reasons for
the instability of HN(CN)2 is the formation of the carbodii-
mide isomer upon protonation, or more general, upon elec-
trophilic attack of the dca anion. Carbodiimides are very
prone to polymerization. According to NBO analysis, at
least three Lewis representations including carbodiimide
structures (A and C, Figure 13) are needed to properly ex-
plain the electronic structure of the dicyanoamide ion. Aris-
ing from a strong delocalization of the out of plane lone
pair (almost pure p atomic orbital) at the central nitrogen
Figure 15. Part of the molecular structure of Li
crystal. Hydrogen atoms of TMEDA are omitted for clarity. Selected
(TMEDA)+dcaꢀ in the
ACHTUNGTRENNUNG
ꢀ
ꢀ
ꢀ
bond lengths [ꢃ] and angles [8]: N1 C2 1.3010(2), N1 C1 1.3075(1), N2
ꢀ
ꢀ
ꢀ
C1 1.1410(1), N2 Li 1.9876(2), N3 C2 1.1473(1), N3 Li 1.9722(2); C1-
N1-C2 118.636(5), N1-C2-N3 173.691(9), N1-C1-N2 174.342(4), C2-N3-Li
155.011(7), C1-N2-Li 156.900(4).
ꢀ
atom into the two p* C N bonds, a lot of the anion charge
sits on the terminal nitrogen atoms, decreasing the basicity
of the central nitrogen atom. The computed partial charges
support this finding since both the central and the terminal
nitrogen atoms possess almost the same value for the nega-
Phenyldicyanoamide
As described before, covalently bound dicyanoamides can
formally be prepared by an alkyl or aryl electrophilic attack
at either the central amide nitrogen atom or at the terminal
nitrogen atoms of the dca anion. Hence, two structural iso-
mers of R(N(CN)2) can be formed as shown in Scheme 2.
According to B3LYP/ACTHUNRGTENN(UG 6-31GAHCUTNGTREN(NNGU d,p) calculations, the carbodii-
mide isomer is favored over the dicyanoamide isomer by
Figure 13. Lewis representations of the dca anion.
10.0 kcalmolꢀ1.
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Chem. Asian J. 2009, 4, 1588 – 1603

Salts and Ionic Liquids of Resonance Stabilized Amides
experimental vibrational data are listed in Table 5 along
with the calculated data.
While structural data of organotin cyanocarbodiimides is
available,[66] no X-ray structure analysis of a covalently
bound dicyanoamide species has been published. Single
Scheme 2. Isomers of PhN(CN)2: phenyldicyanoamide (left) and phenyl-
cyanocarbodiimide (right).
Table 5. Computed and experimental vibrational data of phenyldicyanoa-
mide along with those of K+dcaꢀ (cmꢀ1).
The first report on monomeric aryldicyanoamides was
published by Biechler in 1935 and the first alkyldicyanoa-
mides by Benders and Hackmann in 1972.[57,58] While the
synthesis of elementorganic dicyanoamides/cyanocarbodii-
mides was a research focus of the 1960s to late 1980s,[59,60,61]
recent works mainly deal with the application of covalently
bound dicyanoamides in electro- and polymer chemistry.[62]
Kçhler and Jꢀger were the first who addressed explicitly the
carbodiimide/dicyanoamide problem as they studied phenyl-
dicyanoamide and phenylcyanocarbodiimide.[63] We pre-
pared phenyldicyanoamide in a slightly modified synthetic
procedure from potassium phenylcyanoamide[53] and cyano-
gen bromide in acetonitrile (Scheme 3) and recrystallized
from chloroform.
B3LYP/
6-31G
phenyldicyanoamide K+dcaꢀ
Raman[b]
assignment
(d,p)[a] Raman[b] IR[c]
IR[d]
ns,C
ꢀ
3222
3203
2374
2353
N
3066(7)
2984(3)
3059w
2961w
2264m
2230s
–
–
–
–
H,Ph
nas,C
ꢀ
H,Ph
ns,C ꢂN
nas,CꢂN
2212(10)
2176/
2260s
2139vs
2158(2)
ns,C
1655
1537
1374
1268
1260
N
1592(4)
1462(1)
–
–
1563s
1490vs
1347s
1262s
–
–
–
–
–
–
–
=
C,Ph
nas,C
=
C,Ph
ds,C
ꢀ
H,Ph
nas,C
1322s
915s
ꢀ
N
nC(Ph) N/ns,C
1237vs 914(2)
ꢀ
ꢀ
N
das,C
1214
1066
1015
N
1183(2)
1035(1)
1001(7)
898(1)
752(1)
633(2)
526(1)
1182m
1025w
1003w
902w
748s
–
–
–
-
–
–
–
-
ꢀ
H,Ph
ds,CCC,Ph
das,CCC,Ph
gas,C
918
768
640
532
N
ꢀ
H,Ph
gs,C
ꢀ
–
–
H,Ph
ds,NCN
638m
–
666(2)
–
666m
525s
das,NCN
[a] Unscaled calculated frequencies; in round brackets: IR intensities
(km molꢀ1), Raman activities (ꢃ4 amuꢀ1). [b] Experimental Raman inten-
sity scaled to the maximum value 10. [c] ATR sensor. [d] KBr pellet.
Scheme 3. Synthesis of phenyldicyanoamide.
crystals of phenyldicyanoamide suitable for X-ray structure
analysis have been obtained from recrystallization in chloro-
form. Phenyldicyanoamide crystallizes in the monoclinic
space group P21/c with four units per cell (Table 2).
Figure 16 shows the molecular structure of phenyldicya-
noamide, revealing a non-planar species (dihedral angle N1-
C1-N3-C2=168.98). A slight torsion of the phenyl ring
(19.78) with respect to the NCN plane is also observed. The
According to Kçhler and Jꢀger, phenylcyanocarbodii-
mide[63] can be obtained from the reaction of phenylisocya-
nide dichloride[64] with disodium cyanoamide[65] (Scheme 4),
a reaction which we could not confirm.
ꢀ
ꢀ
N1 C1 and N2 C2 bond lengths are 1.136 ꢃ and 1.145 ꢃ,
respectively, consistent with the presence of a triple bond
Scheme 4. Failed synthesis of phenylcyanocarbodiimide according to Ref-
erence [63].
Similar to alkali dicyanoamides, phenyldicyanoamide is
neither moisture nor air sensitive and is thermally stable up
to 1878C with a melting point of 928C (literature reference:
818C).[63] The 13C NMR spectrum reveals beside the aryl
peaks (133.4, 130.4, 127.5, and 116.1; cf. 139.6–114.4 N-phe-
nylcyanoamide),[55] one resonance in the cyanoamide range
(103.5 ppm, cf. 111.2 ppm for N-phenylcyanoamide
PhN(H)CN).[55] On the other hand, two resonances are
found in the 14N NMR spectrum (ꢀ154 ppm, cf. ꢀ164 ppm
Figure 16. ORTEP drawing of the molecular structure of phenyldicyano-
amide. Thermal ellipsoids with 50% probability at 295 K. Selected bond
ꢀ
ꢀ
ꢀ
lengths [ꢃ] and angles [8]: N1 C1 1.136(3), N3 C1 1.360(3), N3 C3
ꢀ
ꢀ
1.452(3), N2 C2 1.145(3), N3 C2 1.352(3); N1-C1-N3 178.2(3), N3-C3-
C4 119.1(2), C1-N3-C3 121.1(2), N2-C2-N3 179.4(2), C1-N3-C2 117.0(2),
C2-N3-C3 121.4(2).
2,6-dichlorphenyl-15N(H)C15N)[56]
and
ꢀ323 ppm,
cf.
ꢀ322 ppm for 3,5-dichlorphenyl-15N(H)C15N).[56] Selected
Chem. Asian J. 2009, 4, 1588 – 1603
ꢂ 2009 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.chemasianj.org
1595

A. Schulz et al.
FULL PAPERS
(d
G
tional data and assignments are listed in Table 7. Three reso-
nances are observed in the 14N NMR spectrum of nca salt
solutions which are in the typical range of nitramides
1.352 ꢃ and 1.360 ꢃ, indicating a bond order between 1 and
2 ( d
(ꢀ2 ppm, cf. ꢀ9 ppm for [N
(NO2)2]ꢀ),[67] nitramines
ACHTUNGTRENNUNG
(ꢀ165 ppm, cf. ꢀ143 ppm 2-pyridyl-N(H)NO2),[68] and cya-
noamides (ꢀ178 ppm, cf. ꢀ184 ppm for H2NCN), respective-
ly.[46] A single resonance is found for the cyano group in the
13C NMR experiment (116.7 ppm, cf. 111.2 ppm for
PhN(H)CN, N-phenylcyanoamide).[55]
Alkali nitrocyanoamides (nca) can be prepared by the reac-
tion of the base MOH with S-methyl-N-nitroisothiourea[26]
(Scheme 5).[27a,b]
The electronic structure is best described by a series of
different resonance structures such as nitrocarbodiimide
representations (A and B in Figure 17), nitrocyanoamide
Scheme 5. Synthesis of nitrocyanoamide salts (M=Li, Na, Cs (n=1) and
Ba (n=2)).
Crystals of Li+ncaꢀ and Li+ncaꢀ·2H2O are very moisture
sensitive and deliquesce within seconds while all other ex-
amined alkali nca salts can be handled without inert gas at-
mosphere. Unlike the dca and fca salts, all investigated nca
compounds are heat and shock-sensitive. However, they are
thermally stable up to over 2158C and decompose in exo-
thermic reactions upon further heating.[24,28] Results of the
DTA/TGA experiments are listed in Table 6.
Table 6. Thermal properties of alkali nitrocyanoamides and barium nitro-
cyanoamide.
Figure 17. Lewis representations of the nca anion.
M[N
Li[N
Na[N
Cs[N
U
m.p. [8C]
Tdec [8C][a]
loss of mass [%]
[b]
–
215
254
312
293
54
38
19
50
structures C and D, or N-cyanodiazen-N’,N’-dihydroxylate
E. According to NBO analyses, Lewis representations C and
D are the best descriptions of the electronic structure.
Besides powder data,[27a] no single crystal data of the
sodium nitrocyanoamide salt are available so far. Na+ncaꢀ
crystallizes in the monoclinic space group P21/n with four
formula units per cell (Table 2). The molecular structure is
shown in Figure 18.
U
203
93
ACHTUNGTRENNUNG
[b]
N
–
[a] Tdec =decomposition temperature (onset); [b] no m.p. was observed.
The nca anion is easily detected by means of Raman, IR,
and NMR spectroscopy (14N, 13C), as well as FABꢀ. Vibra-
Table 7. Computed and experimental vibrational data of nca salts (cmꢀ1) along with an approximate assignment.
assignment
B3LYP/
6-31G
(d,p)[a]
Li+ncaꢀ
Na+ncaꢀ
Raman[b]
Cs+ncaꢀ
Raman[b]
ACTHNGUTERNNUG
Ba2+(ncaꢀ)2
G
Raman[b]
IR[c]
IR[c]
IR[c]
Raman[b]
IR[c]
nCꢂN
nN=O
2266 (132,241)
1549 (2,386)
1357 (4,626)
1199 (13,22)
965 (14,17)
781 (8,1)
770 (8,1)
590 (6,0)
560 (2,13)
515 (2,13)
200 (4,3)
2229 (10)
1540 (2)
1290 (1)
1173 (5)
982 (5)
–
778 (3)
622 (1)
537 (1)
506 (1)
227 (4)
151 (5)
2211s
1438s
1276vs
1173m
972w
774w
760w
–
2192 (10)
1466 (1)
1319 (2)
1181 (3)
967 (6)
–
774 (5)
610 (2)
547 (1)
515 (2)
230 (2)
135 (3)
2196s
1450s
1287vs
1178/1168m
984/967w
776w
764m
–
2184 (10)
1441 (1)
1257 (1)
1166 (3)
958 (2)
–
766 (5)
599 (1)
–
2178vs
1430s
1260s
1160s
960m
772m
764m
–
2219 (1)
1529 (0.5)
1299 (1)
1178 (8)
982 (10)
–
966 (6)
623 (3)
532 (1)
498 (2)
221 (5)
143 (2)
2212s
1418s
1276vs
1172m
979m
764m
–
nNꢀ
N
nCꢀ
N
dCNN
gONO
dONO
dNNO
–
gNCN
536m
520m
–
545m
511m
–
548m
512m
–
528m
509m
–
gNCN
509 (1)
226 (3)
–
dNC-N-NO2,bending
gNC-N-NO2,twist
144 (0,3)
–
–
–
–
[a] Unscaled calculated frequencies; in round brackets: IR intensities (km molꢀ1), Raman activities (ꢃ4 amuꢀ1). [b] Experimental Raman intensity scaled
to the maximum value 10. [c] ATR sensor.
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Chem. Asian J. 2009, 4, 1588 – 1603

Salts and Ionic Liquids of Resonance Stabilized Amides
Figure 19. Cation–anion interactions in Na+ncaꢀ. Distances in ꢃ.
Figure 18. ORTEP drawing of the molecular structure of Na+ncaꢀ. Ther-
mal ellipsoids with 50% probability at 295 K. Selected bond lengths [ꢃ]
ꢀ
ꢀ
ꢀ
ꢀ
and angles [8]: N1 O1 1.234(1), N1 N2 1.338(1), C N3 1.148(2), N1 O2
ꢀ
ꢀ
1.250(1), N2 C 1.340(2), Na O1 2.369(1); N1-N2-C 111.2(1), Na-O1-N1
143.5(1), O1-N1-N2 122.1, N2-C-N3 172.4(1), O1-N1-O2 122.1(1), O2-
N1-N2 115.8(1).
removal of traces of water or solvent molecules under high
vacuum (HV), is necessary to obtain pure ionic liquids of
the type, for example, BMIM+Xꢀ. Tables 8 and 9 summarize
the spectroscopic data of all ionic liquids of resonance stabi-
lized amides we discuss here.
In contrast to the high energy-density alkali and silver nca
salts,[24,28] the ionic liquids with nitrocyanoamide anion and a
bulky organic cation are neither heat nor shock sensitive,
A great diversity of bonding modes is found for the nca
anion which is surrounded by six sodium cations. The CN
group coordinates two neighboring Na+ centers, the NO2
moiety coordinates three cations through the oxygen atoms
in both mono and bidentate fashion, while the amide nitro-
gen atom also coordinates an additional Na+ (Figure 19).
The Na+ ion is surrounded by three O and three N donor
atoms, leading to a coordination number of six. These strong
cation–anion interactions lead to an interesting three-dimen-
sional network arrangement of the ions in the solid with
chains of Na+ and ncaꢀ stacked one upon the other.[1]
Partial double bond character can be assumed for the N
CN and N NO2 bonds with distances of 1.340(1) ꢃ and
1.338(1) ꢃ, respectively, while the C N3 bond length of
1.148(1) ꢃ corresponds to a triple bond. The resonance sta-
bilized nca anion is almost planar with an O1-N1-N2-C dihe-
dral angle of 3.38.
Table 8. Thermal properties of amide based ionic liquids [RMIM+Xꢀ]
(R=alkyl: E=ethyl, B=n-butyl, H=n-hexyl; MIM=methylimidazoli-
um; X=resonance stabilized amide).
amide
R
M [gmolꢀ1
]
Tm/Tg [8C][a]
Tdec [8C][b]
dca[72]
dfa
fca
nca
dca[73]
dfa
ethyl[72]
ethyl
ethyl
177.21
183.21
180.21
197.20
205.26
211.26
208.26
225.25
233.32
239.32
236.32
253.31
ꢀ12[72]
ꢀ18
ꢀ5
240[72]
213
218
ꢀ
ethyl
27
225
ꢀ
n-butyl[73]
n-butyl
n-butyl
n-butyl
n-hexyl
n-hexyl
n-hexyl
n-hexyl
ꢀ29[73]
ꢀ26
32
240[73]
221
ꢀ
fca
227
234
246
228
231
239
nca
dca
dfa
fca
nca
ꢀ6
ꢀ48
ꢀ41
ꢀ15
ꢀ38
Ionic Liquids
[a] Tm =m.p., Tg =temperature of phase transition. [b] Tdec =decomposi-
tion temperature (onset).
Ionic liquids (ILs) of resonance
stabilized amides are readily
prepared from the reaction of
the amide based pseudohalide
potassium salts with imidazoli-
um tetrafluoroborate salts (e.g.,
ꢀ
BMIM+BF4 ,
Scheme 6).[69]
While the potassium and imida-
zolium salts are soluble in
methanol, potassium tetrafluor-
oborate precipitates and can be
separated by filtration. A spe-
cific drying procedure involving
stepwise addition and removal
of dried methanol, THF, and di-
Scheme 6. Synthesis and post-synthetical treatment procedure of ionic liquids of resonance stabilized amides
(R=ethyl, n-butyl, n-hexyl; X=amide based pseudohalide; HV=high vacuum; ꢃ=addition of dried solvent
chloromethane, followed by the and removal in HV).
Chem. Asian J. 2009, 4, 1588 – 1603
ꢂ 2009 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
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1597

A. Schulz et al.
FULL PAPERS
Table 9. Spectroscopic data of amide based ionic liquids [RMIM+Xꢀ] (R=alkyl: E=ethyl, B=n-butyl, H=n-hexyl; MIM=methylimidazolium; X=res-
onance stablized amide).
amide
dfa
R
Raman[a] [cmꢀ1
]
IR[a] [cmꢀ1
]
d
(13C)[b] [ppm]
d
N
dACTHNGUTERNNUG
(1 H)[b] [ppm]
ethyl
nCH 2860,
nCO 1682, 1575
nCH 2875,
nCO 1687, 1569
nCH 2858,
nCO 1683, 1566
nCH 2859,
nCH 2863,
nCO 1696, 1554
nCH 2876,
nCO 1696, 1561
nCH 2860,
nCO 1697, 1558
nCH 2861,
N-CHO, 181.3
N-CHO, 181.3
N-CHO, 181.3
N-CHO, ꢀ128
N-CHO, ꢀ128
N-CHO, ꢀ128
N-CHO, 8.95
N-CHO, 8.95
N-CHO, 8.95
N-CHO, 8.49
dfa
dfa
fca
n-butyl
n-hexyl
ethyl
N-CHO, 172.9
N-CN, 123.4
N-CN, ꢀ190
nCN 2142,
nCO 1570
nCN 2148,
nCO 1565
N-CHO, ꢀ245
fca
n-butyl
n-hexyl
ethyl
nCH 2867,
nCN 2145,
nCO 1566
nCH 2862,
nCN 2156,
nCO 1576
nCN 2171,
nNO 1570, 1426,
nNN 1259
nCN 2172,
nNO 1566, 1418,
nNN 1265
nCN 2171,
nNO 1569, 1417,
nNN 1261
nCH 2873,
nCN 2150,
nCO 1571
nCH 2859,
nCN 2147,
nCO 1584
nCN 2168,
nNO 1572, 1424,
nNN 1258
nCN 2169,
nNO 1572, 1425,
nNN 1260
nCN 2168,
nNO 1571, 1424,
nNN 1259
N-CHO, 172.9
N-CN, 123.4
N-CN, ꢀ190
N-CHO, 8.49
N-CHO, ꢀ245
fca
N-CHO, 172.9
N-CN, 123.4
N-CN, ꢀ190
N-CHO, 8.49
N-CHO, ꢀ245
nca
nca
nca
dca
N-CN, 116.7
N-CN, 116.7
N-CN, 116.7
N-CN, 118.9
N-NO2, ꢀ2
-
-
-
-
N-NO2, ꢀ165
N-CN, ꢀ178
N-NO2, ꢀ2
n-butyl
n-hexyl
n-hexyl
N-NO2, ꢀ165
N-CN, ꢀ178
N-NO2, ꢀ2
N-NO2, ꢀ165
N-CN, ꢀ178
N-CN, ꢀ229
N-CN, ꢀ368
nCN 2192, 2135
nCN 2228, 2125
[a] Only characteristic vibrations of the anion are listed. [b] Only characteristic shifts of the anion are listed.
and can therefore be prepared and stored in large scale.
Nevertheless, this type of amide based ionic liquids can also
be considered as “energetic ionic liquids” since the thermo-
dynamically unstable amide anion is only kinetically stabi-
melting point. It can be assumed that both the number and
the strength of interionic interactions (coulomb and hydro-
gen bonding) as well as the size of the ions is responsible for
the fairly wide range of observed melting points. So far we
have not been able to crystallize any of the discussed ionic
liquids without solvent. Solidification resulted only in glass
formation, a well-known phenomenon of ionic liquids.[71]
lized by a bulky organic cation such as EMIM+ or BMIM+
[70]
.
Amide based ionic liquids are very hygroscopic and im-
mediately absorb water when exposed to air. The decompo-
sition temperature of amide based ionic liquids ranges, de-
pending on the counterion, between Tdec =2138C [EMIM+
dfaꢀ] and 2468C [HMIM+dcaꢀ] (Table 8). As shown in
Table 8 ionic liquids of CHO- and NO2-substituted amides
are less stable compared to ILs with the dca anion. More-
over, the thermal stability increases along the series EMIM+
Xꢀ <BMIM+Xꢀ <HMIM+Xꢀ. Slow decomposition arising
from hydrolysis of the formyl-based ILs is observed when
exposed to air [Equations (11) and (12)].
Summary
The synthesis, structure, and bonding of alkali salts of reso-
nance stabilized amides such as dfa, fca, nca, and dca are
discussed on the basis of experimental and theoretical data.
X-ray data of K(18-crown-6)+dfaꢀ, K(18-crown-6)+fcaꢀ,
ACTHNUTRGNEUNG
Na+ncaꢀ, and Li(TMEDA)+dcaꢀ reveal almost planar
anions with strong cation–anion interactions resulting in net-
work-like structures in the solid state. For comparison, the
X-ray structures of covalently bound diformamide and phe-
nyldicyanoamide have also been discussed.
½NðCHOÞ2ꢁꢀþH2O ! ½HCO2ꢁꢀþH2NCHO
½NðCHOÞCNꢁꢀþH2O ! ½HCO2ꢁꢀþH2NCN
ð11Þ
ð12Þ
Moreover, novel ionic liquids based on resonance stabi-
lized amides have been prepared and fully characterized.
Their synthesis starts with the potassium salts of the amides
and the imidazolium tetrafluoroborate salts. All new com-
pounds represent room temperature ionic liquids, except for
BMIM+fcaꢀ melting at 328C. These ionic liquids are neither
heat nor shock sensitive, they are thermally stable up to
over 2008C, and can be prepared in large quantities.
The initially colorless dfa-based ILs slowly turn red–
brown, depending on the storage temperature. Hence, these
ILs should be stored under nitrogen at temperatures below
ꢀ58C. All other ILs can be stored at ambient temperature
under nitrogen without any noticeable decomposition.
The experimentally determined melting points vary be-
tween ꢀ488C [HMIM+dcaꢀ] and 328C [BMIM+fcaꢀ]
(Table 8), with the HMIM salts always possessing the lower
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Chem. Asian J. 2009, 4, 1588 – 1603

Salts and Ionic Liquids of Resonance Stabilized Amides
Li+dfaꢀ: Lithium tert-butoxide (1.60 g; 20.0 mmol) was added to a stirred
solution of diformamide (1.50 g; 20.5 mmol) in dried THF (25 mL) at
08C. After stirring for 6 h, the reaction mixture was filtered, the residue
washed with THF, and subsequently dried in vacuum. Yield: 1.48 g
(94%); Tdec,onset =1758C; IR (KBr, 258C): n˜ =2856 (w), 2747 (vw), 1694
(vs), 1604 (vs), 1386 (s), 1370 (s), 1287 (m), 1263 (m), 1055 (w), 785 (m),
618 cmꢀ1 (m); Raman (200 mW, 258C): n˜ =2847 (1), 2766 (2), 1747/1709
(10), 1415 (2), 1313/1308 (1), 1268 (1), 1048 (1), 616 (4), 339 cmꢀ1 (1);
1H NMR ([D6]DMSO, 400 MHz, 258C): d=8.95 ppm (s, CHO);
13C NMR ([D6]DMSO, 101 MHz, 258C): d=181.3 ppm (s, CHO);
Experimental Section
General Information
NMR: 1H, 13C{1H}, and 14N{1H} NMR spectra were obtained on a JEOL
EX 400 NMR spectrometer or on a JEOL EX 270 NMR spectrometer
and were referenced either to protic impurities in the deuterated solvent
(1H) or externally to SiMe4 (13C{1H}) or nitromethane (14N{1H}). IR:
Perkin–Elmer Spectrum One FT-IR spectrometer with a DuraSamplIRII
Diamond ATR sensor from SensIR Technologies or Nicolet 520 FT-IR
spectrometer (KBr pellets). Raman: Perkin–Elmer Spectrum 2000 NIR
FT equipped with a Nd:YAG laser (1064 nm). CHN analyses: Analysator
Elementar Vario EL. MS: Jeol MStation JMS 700. DSC experiments:
Perkin–Elmer Pyris 6 DSC or Setraram DSC 141. DTA/TGA experi-
ments: Setraram TG-DTA 92.
14N NMR ([D6]DMSO, 28.9 MHz, 258C): d=ꢀ128 ppm (s, Dn1/2
=
1301 Hz, N-CHO); MS (FABꢀ, Xenon, 6 keV, m-NBA-matrix), m/z (%):
72 (5) [M], 73 (3) [M+H]; elemental analysis: calcd (%) for C2H2LiNO2
(78.98): C 30.41, H 2.55, N 17.73; found: C 31.35, H 3.22, N 16.58.
K+dfaꢀ: Potassium methoxide (1.10 g 15.7 mmol) was added to a stirred
solution of diformamide (1.20 g; 16.4 mmol) in dried THF (25 mL) at
08C. After stirring for 6 h, the reaction mixture was filtered, the residue
washed with THF, and subsequently dried in vacuum. Yield: 1.62 g
(93%); m.p.: 2378C, Tdec,onset =3848C; IR (KBr, 258C): n˜ =2838 (w), 2771
(w), 1698 (s), 1560 (vs), 1387 (m), 1349 (m), 1282 (s), 1251 (m), 1130 (w),
740 (m), 610 cmꢀ1 (m); Raman (200 mW, 258C): n˜ =2853 (1), 2771 (2),
1668 (10), 1421 (3), 1409 (1), 1294 (1), 1258 (2), 1051 (1), 593 (8),
317 cmꢀ1 (2); 1H NMR ([D6]DMSO, 400 MHz, 258C): d=8.95 ppm (s,
CHO); 13C NMR ([D6]DMSO, 101 MHz, 258C): d=181.3 ppm (s, CHO);
X-ray Structure Determination
X-ray quality crystals of all considered species were selected in silicon oil
at RT. All samples were mounted on a glass fiber and cooled to 200(2) K
during measurement. Data for compounds Hdfa and Pfdca were collect-
ed on a NONIUS KappaCCD diffractometer, data for compounds Na+
ncaꢀ and Li
ACHTUNGTRENNUNG(edta)dca were collected on a STOE IPDS diffractometer,
and K(18-crown-6)+dfaꢀ and K(18-crown-6)+fcaꢀ on a NONIUS CAD4
using Mo Ka radiation (l=0.71073). Crystallographic data are summar-
ized in Table 2. Selected bond lengths and angles are available in
Figure 2, 7, 10, 16, and 18. The structures were solved by direct methods
14N NMR ([D6]DMSO, 28.9 MHz, 258C): d=ꢀ128 ppm (s, Dn1/2
=
1301 Hz, N-CHO); MS (FABꢀ, Xenon, 6 keV, m-NBA-matrix), m/z (%):
72 (2) [M], 73 (2) [M+H]; elemental analysis: calcd (%) for C2H2KNO2
(111.14): C 21.61, H 1.81, N 12.60; found: C 21.22, H 1.70, N 12.09.
(SHELXS-97 (LiACHTUNGTRENNUNG
(Edta)dca, K(18-crown-6)+fcaꢀ, K(18-crown-6)+dfaꢀ),
SIR-97 (Phdca, Nanca, and Hdfa)[72, 73] and refined by full-matrix least
squares procedures (SHELXL-97).[74] All non hydrogen atoms were re-
Na+fcaꢀ: A solution of cyanoamide (1.00 g; 23.8 mmol) in dried metha-
nol (10 mL) was added slowly to a stirred solution of sodium methoxide
(1.29 g; 23.8 mmol) in dried methanol (40 mL) at 08C. After stirring for
30 min, the reaction mixture was heated to boiling and ethyl formate
(5.80 mL; 5.34 g, 72.0 mmol) was added. After 3 h reflux, all volatiles
were removed in vacuum and the residue was dried in vacuum. Yield:
2.15 g (98%); m.p.: 2538C; Tdec,onset =3018C; IR (KBr, 258C): n˜ =2882
(w), 2207 (s), 1597 (vs), 1384 (m), 1320 (s), 1086 (m), 963 (w), 638 (w),
608 (m), 524 cmꢀ1 (m); Raman (200 mW, 258C): n˜ =2882 (3), 2180 (10),
1578 (4), 1383 (3), 1329/1300 (4), 984 (3), 843 (3), 613 (1), 522 (1), 216
(4), 132 cmꢀ1 (5); 1H NMR ([D6]DMSO, 400 MHz, 258C): d=8.49 ppm
(s, CHO); 13C NMR ([D6]DMSO, 101 MHz, 258C): d=172.9 (s, CHO),
123.4 ppm (s, CN); 14N NMR ([D6]DMSO, 28.9 MHz, 258C): d=ꢀ190 (s,
Dn1/2 =1156 Hz, CN), ꢀ245 ppm (s, Dn1/2 =1927 Hz, N-CHO); MS (FABꢀ,
Xenon, 6 keV, m-NBA-matrix), m/z (%): 69 (27) [M]; elemental analysis:
calcd (%) for C2HN2NaO (92.03): C 26.10, H 1.10, N 30.44; found:
C 25.86, H 1.21, N 29.91.
Li+fcaꢀ: A solution of cyanoamide (1.00 g; 23.8 mmol) in 10 mL dried
methanol was added slowly to a stirred solution of lithium tert-butoxide
(1.90 g; 23.8 mmol) in dried methanol (40 mL) at 08C. After stirring for
30 min, the reaction mixture was heated to boiling and ethyl formate
(5.80 mL; 5.34 g, 72.0 mmol) was added. After 3 h reflux, all volatiles
were removed in vacuum and the residue was dried in vacuum. Yield:
1.72 g (95%); Tdec,onset =1948C; IR (KBr, 258C): n˜ =2896 (w), 2202 (s),
1589 (vs), 1388 (m), 1334 (s), 1090 (w), 1001 (w), 640 (w), 600 (m),
540 cmꢀ1 (m); Raman (200 mW, 258C): n˜ =2910 (2), 2210 (10), 1594/1573
(2), 1384 (3), 1328 (9), 1006 (2), 864 (3), 617 (1), 604 (1), 543 (1), 262 (9),
158 cmꢀ1 (4); 1H NMR ([D6]DMSO, 400 MHz, 258C): d=8.49 ppm (s,
CHO); 13C NMR ([D6]DMSO, 101 MHz, 258C): d=172.9 (s, CHO),
123.4 ppm (s, CN); 14N NMR ([D6]DMSO, 28.9 MHz, 258C): d=ꢀ190 (s,
Dn1/2 =1156 Hz, CN), ꢀ245 ppm (s, Dn1/2 =1927 Hz, N-CHO); MS (FABꢀ,
Xenon, 6 keV, m-NBA-matrix), m/z (%): 69 (21) [M]; elemental analysis:
calcd (%) for C2HLiN2O (75.98): C 31.62, H 1.33, N 36.87; found:
C 32.46, H 1.87, N 35.94.
fined anisotropically. In LiACTHNUGRTENUNG(Etda)dca the hydrogen atoms were included
in the refinement at calculated positions using a riding model, in Hdfa
and Phdca the hydrogen atoms were refined freely.
Synthetic Procedures
Hdfa: HCl (4.70 L; 0.21 mol) gas was added to a stirred suspension of
sodium diformylamide (13.28 g; 0.14 mol) in dried diethyl ether (400 mL)
at 08C. This mixture was allowed to warm up to ambient temperature
and stirred for 3 h before filtration. The residue was washed with diethyl
ether (200 mL), and the combined ether phases were concentrated. Addi-
tion of n-hexane (60 mL) yielded colorless crystals. Yield: 6.95 g (68%);
m.p.: 448C; b.p.: 1988C; IR (KBr, 258C): n˜ =3262 (s), 2917 (m), 2898
(sh), 1745 (s), 1686 (vs), 1480 (m), 1412 (w), 1373/1347 (m), 1264 (m),
1188 (s), 1088/1041 (w), 796 (m), 649 (s), 527 cmꢀ1 (m); Raman
(200 mW, 258C): n˜ =3256 (1), 2955 (2), 2934 (1), 1739/1719 (10), 1450 (1),
1431 (5), 1372/1359 (0.4), 1264 (1), 1192/1167 (0.4), 1090/1077 (0.5), 1038
(0.3), 769 (0.3), 547 (9), 231 (1), 142 cmꢀ1 (5); 1H NMR ([D6]DMSO,
400 MHz, 258C): d=11.16 (s, 1H, NH), 8.83 ppm (s, 2H, CHO);
13C NMR ([D6]DMSO, 101 MHz, 258C): d=167.2 ppm (s, CHO);
14N NMR ([D6]DMSO, 28.9 MHz, 258C): d=ꢀ207 ppm (s, Dn1/2 =507 Hz,
N-CHO); MS (EI+, 70 eV, >5%), m/z (%): 73 (95) [M], 45 (100)
[MꢀCO], 44 (44) [MꢀCHO], 43 (15) [MꢀHꢀCHO], 29 (51) [CHO], 28
(23) [CO]; elemental analysis: calcd (%) for C2H3NO2 (73.05): C 32.88,
H 4.14, N 19.17; found: C 32.59, H 4.31, N 18.98.
Na+dfaꢀ: Sodium methoxide (0.72 g; 13.3 mmol) was added to a stirred
solution of diformamide (1.00 g 13.7 mmol) in dried THF ( 25 mL) at
08C. After stirring for 6 h, the reaction mixture was filtered, the residue
washed with THF and subsequently dried in vacuum. Yield: 1.23 g
(97%); m.p.: 2428C, Tdec,onset =2868C; IR (KBr, 258C): n˜ =2833 (m),
2716 (w), 1694 (s), 1591 (vs), 1388 (m), 1363 (s), 1291 (m), 1264 (m), 1089
(w), 778 (m), 605 cmꢀ1 (m); Raman (200 mW, 258C): n˜ =2862 (2), 2776
(2), 1677 (10), 1422 (3), 1405 (1), 1274 (1), 1261 (2), 1063 (1), 602 (8),
320 cmꢀ1 (2); 1H NMR ([D6]DMSO, 400 MHz, 258C): d=8.95 ppm (s,
CHO); 13C NMR ([D6]DMSO, 101 MHz, 258C): d=181.3 ppm (s, CHO);
K+fcaꢀ: A solution of cyanoamide (1.00 g; 23.8 mmol) in dried methanol
(10 mL) was added slowly to a stirred solution of potassium methoxide
(1.67 g; 23.8 mmol) in dried methanol (40 mL) at 08C. After stirring for
30 min, the reaction mixture was heated to boiling and ethyl formate
(5.80 mL; 5.34 g, 72.0 mmol) was added. After 3 h reflux, all volatiles
were removed in vacuum and the residue was dried in vacuum. Yield:
14N NMR ([D6]DMSO, 28.9 MHz, 258C): d=ꢀ128 ppm (s, Dn1/2
=
1301 Hz, N-CHO); MS (FABꢀ, Xenon, 6 keV, m-NBA-matrix), m/z (%):
72 (3) [M], 73 (2) [M+H]; elemental analysis: calcd (%) for
C2H2NNaO2 (95.03): C 25.28, H 2.12, N 14.74; found: C 24.85, H 2.21,
N 14.25.
Chem. Asian J. 2009, 4, 1588 – 1603
ꢂ 2009 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
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1599

A. Schulz et al.
FULL PAPERS
2.49 g (97%); m.p.: 1828C; Tdec,onset =2598C; IR (KBr, 258C): n˜ =2857
(m), 2196 (s), 1622 (vs), 1402 (m), 1313 (s), 1080 (s), 930 (w), 642 (m),
592 (m), 553 cmꢀ1 (w); Raman (200 mW, 258C): n˜ =2857 (3), 2178/2142
(9), 1606/1592 (2), 1402 (5), 1330/1306 (1), 1001 (1), 882 (1), 642 (10), 611
(1), 230 (4), 140 cmꢀ1 (3); 1H NMR ([D6]DMSO, 400 MHz, 258C): d=
8.49 ppm (s, CHO); 13C NMR ([D6]DMSO, 101 MHz, 258C): d=172.9 (s,
CHO), 123.4 ppm (s, CN); 14N NMR ([D6]DMSO, 28.9 MHz, 258C): d=
ꢀ190 (s, Dn1/2 =1156 Hz, CN), ꢀ245 ppm (s, Dn1/2 =1927 Hz, N-CHO);
MS (FABꢀ, Xenon, 6 keV, m-NBA-matrix), m/z (%): 69 (24) [M]; ele-
mental analysis: calcd (%) for C2HKN2O (108.14): C 22.21, H 0.93,
N 25.90; found: C 21.92, H 1.29, N 26.51.
Ag+fcaꢀ: Sodium formylcyanoamide (0.50 g; 5.43 mmol) was slowly
added to a solution of silver nitrate (0.90 g; 5.30 mmol) in H2O (40 mL;
acidified by 3 drops of conc. HNO3) at 08C in a dark room. After stirring
for 15 min at 08C, the Ag+fcaꢀ was filtered and washed with H2O
(25 mL), ethanol, and diethyl ether. The Ag+fcaꢀ was dried in vacuum
for 30 min. Yield: 0.89 g (95%); IR (ATR, 258C): n˜ =2894 (w), 2184 (s),
1614 (s), 1396 (w), 1292 (m), 1084 cmꢀ1 (w); Raman (100 mW, 258C): n˜ =
2916 (2), 2181 (10), 1598 (2), 1390 (2), 1319 (1), 634 (6), 607 (1), 556 (1),
236 cmꢀ1 (3); elemental analysis: calcd (%) for C2HAgN2O (176.91):
C 13.58, H 0.57, N 15.83; found: C 13.72, H 0.72, N 16.06.
(s), 1450 (s), 1287 (vs), 1178/1168 (m), 984/967 (w), 776 (w), 764 (m), 545
(m), 511 cmꢀ1 (m); Raman (200 mW, 258C): n˜ =2192 (10), 1466 (1), 1319
(2), 1181 (3), 967 (6), 774 (5), 610 (2), 547 (1), 515 (2), 230 (2), 135 cmꢀ1
(3); 13C NMR ([D6]DMSO, 101 MHz, 258C): d=116.7 ppm (s, CN);
14N NMR ([D6]DMSO, 28.9 MHz, 258C): d=ꢀ2 (s, Dn1/2 =23 Hz, N-
NO2), ꢀ165 (s, Dn1/2 =407 Hz, N-NO2), ꢀ178 ppm (s, Dn1/2 =211 Hz, CN);
MS (FABꢀ, Xenon, 6 keV, m-NBA-matrix), m/z (%): 86 (78) [M]; ele-
mental analysis: calcd (%) for CN3NaO2 (109.02): C 11.02, N 38.54;
found: C 10.78, N 38.03.
Li+ncaꢀ: A solution of lithium hydroxide (0.39 g; 16.3 mmol) in H2O
(5 mL) was added to a boiling suspension of S-methyl-N-nitroisothiourea
(2.20 g; 16.3 mmol) in isopropanol (40 mL). After stirring for 40 min at
this temperature, the reaction mixture was allowed to cool to ambient
temperature and was subsequently neutralized with hydrochloric acid
(2 n). After removal of the solvent, the residue was dried in vacuum. Re-
crystallization from acetone and drying in vacuum (4 d at 608C) yielded
Li+ncaꢀ (1.23 g; 81%); Tdec,onset =2158C; IR (ATR, 258C): n˜ =2211 (s),
1438 (s), 1276 (vs), 1173 (m), 972 (w), 774 (w), 760 (w), 536 (m),
520 cmꢀ1 (m); Raman (200 mW, 258C): n˜ =2229 (10), 1540 (2), 1290 (1),
1173 (5), 982 (5), 778 (3), 622 (1), 537 (1), 506 (1), 227 (4), 151 cmꢀ1 (5);
13C NMR ([D6]DMSO, 101 MHz, 258C): d=116.7 ppm (s, CN); 14N NMR
([D6]DMSO, 28.9 MHz, 258C): d=ꢀ2 (s, Dn1/2 =23 Hz, N-NO2), ꢀ165 (s,
Dn1/2 =407 Hz, N-NO2), ꢀ178 ppm (s, Dn1/2 =211 Hz, CN). MS (FABꢀ,
Xenon, 6 keV, m-NBA-matrix), m/z (%): 86 (80) [M]; elemental analysis:
calcd (%) for CLiN3O2 (92.97): C 12.92, N 45.20; found: C 12.27, N 44.53.
Phfca:
A solution of BrCN (2.12 g; 0.02 mol) in dried acetonitrile
(20 mL) was added to a heavily stirred solution of potassium phenylfor-
mylamide (3.18 g; 0.02 mol) in dried acetonitrile (50 mL) at ambient tem-
perature. After stirring for 16 h, the KBr was filtered and the solvent was
removed in vacuum. Recrystallization from chloroform yielded Phfca
(1.58 g; 54%). M.p.: 558C; b.p.: 1958C; IR (ATR, 258C): n˜ =3066 (w),
2953 (w), 2908 (w), 2265/2229 (m), 1664 (vs), 1592 (m), 1490 (s), 1386
(w), 1346 (m), 1182 (s), 1149 (s), 1125 (m), 1072 (m), 1012 (m), 1002 (w),
965 (w), 918 (w), 725 (s), 639 cmꢀ1 (m); Raman (200 mW, 258C): n˜ =3067
(7), 2985 (8), 2906 (1), 2262/2237 (2), 1756 (4), 1596 (5), 1498 (0.5), 1438
(1), 1341 (3), 1341 (3), 1179 (1), 1160 (1), 1124 (0.5), 1026 (2), 1002 (10),
937 (1), 912 (0.5), 748 (3), 614 (1), 539 (3), 483 cmꢀ1 (1); 1H NMR
([D1]CDCl3, 400 MHz, 258C): d=9.02 (s, 1H, CHO), 7.50–7.18 ppm (m,
5H, Ph); 13C NMR ([D1]CDCl3, 101 MHz, 258C): d=163.5 (s, CHO),
130.7 (s, Ph, ipso), 129.7 (s, Ph, para), 129.4 (s, Ph, meta), 127.3 (s, Ph,
ortho), 116.3 ppm (s, CN); 14N NMR ([D1]CDCl3, 28.9 MHz, 258C): d=
ꢀ159 (s, Dn1/2 =445 Hz, CN), ꢀ203 ppm (s, Dn1/2 =792 Hz, N-CHO); MS
(EI+, 70 eV, >0.5%), m/z (%): 146 (1) [M], 121 (100) [MꢀCN+H], 118
Cs+ncaꢀ:
A solution of cesium hydroxide monohydrate (1.31 g;
7.80 mmol) in H2O (5 mL) was added to a boiling suspension of S-
methyl-N-nitroisothiourea (1.06 g; 7.79 mmol) in isopropanol (40 mL).
After 40 min stirring at this temperature, the reaction mixture was al-
lowed to cool to ambient temperature and was subsequently neutralized
with hydrochloric acid (2 n). After removal of the solvent, the residue
was dried in vacuum. Recrystallization from acetone and drying in
vacuum (1 d at 608C) yielded Cs+ncaꢀ (1.57 g; 92%). M.p.: 938C,
T
dec,onset =3128C; IR (ATR, 258C): n˜ =2178 (vs), 1430 (s), 1260 (s), 1160
(s), 960 (m), 772 (m), 764 (m), 548 (m), 512 cmꢀ1 (m); Raman (200 mW,
258C): n˜ =2184 (10), 1441 (1), 1257 (1), 1166 (3), 958 (2), 766 (5), 599
(1), 509 (1), 226 cmꢀ1 (3); 13C NMR ([D6]DMSO, 101 MHz, 258C): d=
116.7 ppm (s, CN); 14N NMR ([D6]DMSO, 28.9 MHz, 258C): d=ꢀ2 (s,
Dn1/2 =23 Hz, N-NO2), ꢀ165 (s, Dn1/2 =407 Hz, N-NO2), ꢀ178 ppm (s,
Dn1/2 =211 Hz, CN); MS (FABꢀ, Xenon, 6 keV, m-NBA-matrix), m/z
(%): 86 (77) [M]; elemental analysis: calcd (%) for CCsN3O2 (218.94):
C 5.49, N 19.19; found; C 5.24, N 18.84.
(5) [MꢀCO], 92 (9) [MꢀCNꢀCO], 77 (16) [MꢀN
ACHTUNGTREN(NUNG CHO)CN]; elemental
analysis: calcd (%) for C8H6N2O (146.15): C 65.75, H 4.14, N 19.17;
found; C 65.86, H 4.25, N 18.92.
Phdca: A solution of BrCN (2.12 g; 0.02 mol) in dried acetonitrile
(20 mL) was added to a heavily stirred solution of potassium phenylcya-
noamide (3.12 g; 0.02 mol) in dried acetonitrile (50 mL) at ambient tem-
perature. After stirring for 16 h, the KBr was filtered and the solvent was
removed in vacuum. Recrystallization from chloroform yielded Phdca
(1.67 g; 58%). M.p.: 928C; b.p.: 1878C; IR (ATR, 258C): n˜ =3059 (w),
2961 (w), 2264 (m), 2230 (s), 1563 (s), 1490 (vs), 1347 (s), 1262 (s), 1237
(vs), 1182 (m), 1025 (w), 1003 (w), 902 (w), 748 (s), 638 cmꢀ1 (m); Raman
(200 mW, 258C): n˜ =3066 (7), 2984 (3), 2262 (10), 2225 (2), 1592 (4), 1462
(1), 1240 (6), 1183 (2), 1035 (1), 1001 (7), 898 (1), 752 (1), 633 (2),
526 cmꢀ1 (1); 1H NMR ([D1]CDCl3, 400 MHz, 258C): d=7.53–7.29 ppm
(m, 5H, Ph); 13C NMR ([D1]CDCl3, 101 MHz, 258C): d=133.4 (s, Ph,
ipso), 130.4 (s, Ph, meta), 127.5 (s, Ph, para), 116.1 (s, Ph, ortho),
103.5 ppm (s, CN); 14N NMR ([D1]CDCl3, 28.9 MHz, 258C): d=ꢀ154 (s,
Dn1/2 =550 Hz, CN), ꢀ323 ppm (s, Dn1/2 =852 Hz, Ph-N); MS (EI+,
70 eV,> 5%), m/z (%): 143 (100) [M], 117 (9) [MꢀCN], 91 (30) [Mꢀ2
CN], 77 (100) [MꢀN(CN)2]; elemental analysis: calcd (%) for C8H5N3
(143.15): C 67.13, H 3.52, N 29.35; found; C 67.44, H 3.42, N 29.64.
ACTHNGUTERNNUG
Ba2+(ncaꢀ)2: Barium hydroxide octahydrate (1.53 g; 4.85 mmol) was
added to a boiling suspension of S-methyl-N-nitroisothiourea (1.31 g;
9.69 mmol) in isopropanol (40 mL) and H2O (60 mL) in five portions
(time interval 1.5 h). After stirring for 3 h at this temperature, the reac-
tion mixture was allowed to cool down to ambient temperature and was
subsequently neutralized with hydrochloric acid (2 n). After removal of
the solvent, the residue was dried in vacuum. Recrystallization from ace-
ACTHNUTRGNEUNG
tone and drying in vacuum (1 d at 608C) yielded Ba2+(ncaꢀ)2 (1.08 g;
72%). Tdec,onset =2938C; IR (ATR, 258C): n˜ =2212 (s), 1418 (s), 1276 (vs),
1172 (m), 979 (m), 764 (m), 528 (m), 509 cmꢀ1 (m); Raman (200 mW,
258C): n˜ =2219 (9), 1529 (0.5), 1299 (1), 1177 (8), 982 (10), 766 (6), 623
(3), 532 (1), 498 (2), 221 (5), 143 cmꢀ1 (2); 13C NMR ([D6]DMSO,
101 MHz, 258C): d=116.7 ppm (s, CN); 14N NMR ([D6]DMSO,
28.9 MHz, 258C): d=ꢀ2 (s, Dn1/2 =23 Hz, N-NO2), ꢀ165 (s, Dn1/2
=
407 Hz, N-NO2), ꢀ178 ppm (s, Dn1/2 =211 Hz, CN). MS (FABꢀ, Xenon,
6 keV, m-NBA-matrix), m/z (%): 86 (81) [M]; elemental analysis: calcd
(%) for C2BaN6O4 (309.38): C 7.76, N 27.16; found: C 7.53, N 26.74.
EMIM+dfaꢀ: Potassium diformylamide (0.68 g; 6.12 mmol) was added to
Na+ncaꢀ: A solution of sodium hydroxide (0.59 g; 14.8 mmol) in H2O
(5 mL) was added to a boiling suspension of S-methyl-N-nitroisothiourea
(2.00 g; 14.8 mmol) in isopropanol (40 mL). After stirring for 40 min at
this temperature, the reaction mixture was allowed to cool to ambient
temperature and was subsequently neutralized with hydrochloric acid
(2 n). After removal of the solvent, the residue was dried in vacuum. Re-
crystallization from acetone and drying in vacuum yielded Na+ncaꢀ
(1.44 g; 89%). M.p.: 2038C; Tdec,onset =2548C; IR (ATR, 258C): n˜ =2196
a solution of 1-ethyl-3-methylimidazolium tetrafluoroborate (1.13 g;
5.71 mmol) in dried methanol (50 mL) at RT. After stirring for 20 h at
RT, the reaction mixture was filtered. Removal of the solvent in vaccum,
followed by a specific drying procedure (see Scheme 6) and drying for
7 d in vacuum (10ꢀ3 Torr), yielded a red-brown ionic liquid (0.94 g;
90%). M.p.: ꢀ188C; Tdec,onset =2138C; IR (ATR, 258C): n˜ =3151 (w),
3084 (m), 2982 (w), 2863 (w), 1696 (m), 1554 (vs), 1470 (w), 1269 (s),
1232 (m), 1170 (s), 1052 (s), 732 (m), 623 cmꢀ1 (m); Raman (200 mW,
1600
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ꢂ 2009 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Chem. Asian J. 2009, 4, 1588 – 1603

Salts and Ionic Liquids of Resonance Stabilized Amides
258C): n˜ =3073 (6), 2966 (10), 2860 (1), 1682 (8), 1575 (1), 1455 (5), 1421
(7), 1338 (5), 1097 (1), 1023 (5), 959 (1), 589 cmꢀ1 (8); 1H NMR
([D6]DMSO, 400 MHz, 258C): d=8.95 ppm (N-CHO); 13C NMR
([D6]DMSO, 101 MHz, 258C): d=181.3 ppm (N-CHO); 14N NMR
([D6]DMSO, 28.9 MHz, 258C): d=ꢀ128 ppm (N-CHO); elemental analy-
sis: calcd (%) for C8H13N3O2 (183.21): C 52.45, H 7.15, N 22.94; found;
C 52.12, H 6.84, N 22.45.
EMIM+fcaꢀ: Potassium formylcyanoamide (0.65 g; 6.01 mmol) was
added to a solution of 1-ethyl-3-methylimidazolium tetrafluoroborate
(1.16 g; 5.86 mmol) in dried methanol (50 mL) at RT. After stirring for
20 h at RT, the reaction mixture was filtered. Removal of the solvent in
vaccum, followed by a specific drying procedure (see Scheme 6) and
drying for 7 d in vacuum (10ꢀ3 Torr), yielded a colorless ionic liquid
(1.01 g; 96%). M.p.: ꢀ58C; Tdec,onset =2188C; IR (ATR, 258C): n˜ =3143
(m), 3067 (s), 2861 (w), 2148 (s), 1565 (vs), 1304 (m), 1168 (vs), 829 (m),
754 (m), 700 (w), 646 (w), 619 cmꢀ1 (m); Raman (200 mW, 258C): n˜ =
2859 (7), 2142 (6), 1570 (3), 1447 (5), 1423 (10), 1387 (6), 1342 (5), 1253
(3), 1096 (4), 1025 (8), 961 (4), 833 (2), 702 (3), 600 cmꢀ1 (6); 1H NMR
([D6]DMSO, 400 MHz, 258C): d=8.49 ppm (N-CHO); 13C NMR
([D6]DMSO, 101 MHz, 258C): d=172.9 (N-CHO), 123.4 ppm (N-CN);
14N NMR ([D6]DMSO, 28.9 MHz, 258C): d=ꢀ190 (N-CN), ꢀ245 ppm
(N-CHO); elemental analysis: calcd (%) for C8H12N4O (180.21): C 53.32,
H 6.71, N 31.09; found; C 53.07, H 6.24, N 30.62.
EMIM+ncaꢀ: Potassium nitrocyanoamide (0.83 g; 6.63 mmol) was added
to a solution of 1-ethyl-3-methylimidazolium tetrafluoroborate (1.25 g;
6.31 mmol) in dried methanol (50 mL) at RT. After stirring for 20 h at
RT, the reaction mixture was filtered. Removal of the solvent in vaccum,
followed by a specific drying procedure (see Scheme 6) and drying for
7 d in vacuum (10ꢀ3 Torr), yielded a colorless glass (1.21 g; 97%). M.p.:
278C; Tdec,onset =2258C; IR (ATR, 258C): n˜ =3150 (w), 3110 (m), 2986
(w), 2168 (s), 1572 (m), 1424 (s), 1258 (vs), 1166 (s), 1152 (m), 951 (w),
842 (w), 760 (w), 701 (w), 647 (w), 621 cmꢀ1 (w); Raman (200 mW,
258C): n˜ =3171 (2), 2988 (5), 2962 (6), 2945 (6), 2171 (10), 1570 (1), 1450
(4), 1426 (6), 1386 (3), 1335 (3), 1259 (2), 1153 (6), 1089 (4), 1023 (5), 953
(6), 762 (8), 704 (1), 598 (5), 502 cmꢀ1 (2); 13C NMR ([D6]DMSO,
101 MHz, 258C): d=116.7 ppm (N-CN); 14N NMR ([D6]DMSO,
28.9 MHz, 258C): d=ꢀ2 (N-NO2), ꢀ165 (N-NO2), ꢀ178 ppm (N-CN); el-
emental analysis: calcd (%) for C7H11N5O2 (197.20): C 42.64, H 5.62,
N 35.51; found: C 42.07, H 5.14, N 34.89.
BMIM+dfaꢀ: Potassium diformylamide (1.09 g; 9.81 mmol) was added to
a solution of 1-n-butyl-3-methylimidazolium tetrafluoroborate (2.04 g;
9.03 mmol) in dried methanol (50 mL) at RT. After stirring for 20 h at
RT, the reaction mixture was filtered. Removal of the solvent in vaccum,
followed by a specific drying procedure (see Scheme 6) and drying for
7 d in vacuum (10ꢀ3 Torr), yielded a red-brown ionic liquid (1.74 g;
91%). M.p.: ꢀ268C; Tdec,onset =2218C; IR (ATR, 258C): n˜ =3157 (m),
3114 (m), 2963 (m), 2938 (m), 2876 (m), 1696 (s), 1561 (vs), 1466 (w),
1386 (w), 1272 (m), 1169 (s), 1049 (vs), 1036 (vs), 849 (w), 752 (w), 732
(w), 652 (w), 623 (m); Raman (200 mW, 258C): n˜ =2967 (8), 2875 (6),
1687 (7), 1569 (7), 1451 (8), 1420 (10), 1390 (8), 1342 (9), 1117 (7), 1025
(9), 767 (8), 589 cmꢀ1 (9); 1H NMR ([D6]DMSO, 400 MHz, 258C): d=
8.95 ppm (N-CHO); 13C NMR ([D6]DMSO, 101 MHz, 258C): d=
181.3 ppm (N-CHO); 14N NMR ([D6]DMSO, 28.9 MHz, 258C): d=
ꢀ128 ppm (N-CHO); elemental analysis: calcd (%) for C10H17N3O2
(211.26): C 56.85, H 8.11, N 19.89; found: C 56.37, H 7.86, N 19.28.
CHO); 13C NMR ([D6] DMSO, 101 MHz, 258C): d=172.9 (N-CHO),
123.4 ppm (N-CN); 14N NMR ([D6]DMSO, 28.9 MHz, 258C): d=ꢀ190
(N-CN), ꢀ245 ppm (N-CHO); elemental analysis: calcd (%) for
C10H16N4O (208.26): C 57.67, H 7.74, N 26.90; found: C 57.35, H 7.59,
N 26.44.
BMIM+ncaꢀ: Potassium nitrocyanoamide (1.12 g; 8.95 mmol) was added
to a solution of 1-n-butyl-3-methylimidazolium tetrafluoroborate (1.89 g;
8.36 mmol) in dried methanol (50 mL) at RT. After stirring for 20 h at
RT, the reaction mixture was filtered. Removal of the solvent in vaccum,
followed by a specific drying procedure (see Scheme 6) and drying for
7 d in vacuum (10ꢀ3 Torr), yielded a colorless ionic liquid (1.74 g; 91%).
M.p.: ꢀ68C; Tdec,onset =2348C; IR (ATR, 258C): n˜ =3149 (m), 3109 (m),
2961 (m), 2936 (m), 2169 (s), 1572 (m), 1425 (s), 1260 (vs), 1165 (s), 950
(w), 844 (w), 760 (w), 650 cmꢀ1 (vs); Raman (200 mW, 258C): n˜ =3164
(2), 3122 (1), 2962 (7), 2941 (6), 2172 (10), 1566 (1), 1447 (3), 1418 (4),
1387 (2), 1341 (2), 1265 (1), 1153 (3), 1116 (1), 1024 (4), 953 (5), 763 (5),
625 (1), 592 (3), 502 cmꢀ1 (1); 13C NMR ([D6] DMSO, 101 MHz, 258C):
d=116.7 ppm (N-CN); 14N NMR ([D6]DMSO, 28.9 MHz, 258C): d=ꢀ2
(N-NO2), ꢀ165 (N-NO2), ꢀ178 ppm (N-CN); elemental analysis: calcd
(%) for C9H15N5O2 (225.25): C 47.99, H 6.71, N 31.09; found: C 47.53,
H 6.64, N 30.74.
HMIM+dfaꢀ: Potassium diformylamide (0.92 g; 8.28 mmol) was added to
a solution of 1-n-hexyl-3-methylimidazolium tetrafluoroborate (1.95 g;
7.67 mmol) in dried methanol (50 mL) at RT. After stirring for 20 h at
RT, the reaction mixture was filtered. Removal of the solvent in vaccum,
followed by a specific drying procedure (see Scheme 6) and drying for
7 d in vacuum (10ꢀ3 Torr), yielded
a red-brown ionic liquid (1.69 g
(92%). M.p.: ꢀ418C; Tdec,onset =2288C; IR (ATR, 258C): n˜ =3153 (w),
3105 (w), 2958 (m), 2932 (m), 2860 (m), 1697 (m), 1558 (vs), 1467 (w),
1380 (w), 1271 (m), 1169 (m), 1053 (s), 732 (w), 623 cmꢀ1 (w); Raman
(200 mW, 258C): n˜ =2935 (7), 2858 (6), 1683 (9), 1566 (9), 1415 (10), 1388
(9), 1336 (10), 1119 (8), 1027 (9), 898 (8), 766 (9), 588 (9), 419 cmꢀ1 (9);
1H NMR ([D6]DMSO, 400 MHz, 258C): d=8.95 ppm (N-CHO);
13C NMR ([D6]DMSO, 101 MHz, 258C): d=181.3 ppm (N-CHO);
14N NMR ([D6]DMSO, 28.9 MHz, 258C): d=ꢀ128 ppm (N-CHO); ele-
mental analysis: calcd (%) for C12H21N3O2 (239.32): C 60.23, H 8.84,
N 17.56; found: C 59.94, H 8.52, N 17.09.
HMIM+fcaꢀ: Potassium formylcyanoamide (0.97 g; 8.97 mmol) was
added to a solution of 1-n-hexyl-3-methylimidazolium tetrafluoroborate
(2.13 g; 8.38 mmol) in dried methanol (50 mL) at RT. After stirring for
20 h at RT, the reaction mixture was filtered. Removal of the solvent in
vaccum, followed by a specific drying procedure (see Scheme 6) and
drying for 7 d in vacuum (10ꢀ3 Torr), yielded a colorless ionic liquid
(1.88 g; 95%). M.p.: ꢀ158C; Tdec,onset =2318C; IR (ATR, 258C): n˜ =3146
(w), 3094 (w), 2956 (m), 2931 (m), 2859 (w), 2147 (s), 1584 (vs), 1466 (w),
1380 (w), 1303 (s), 1167 (m), 1065 (w), 961 (w), 830 (w), 760 (w),
623 cmꢀ1 (w); Raman (200 mW, 258C): n˜ =2960 (10), 2940 (9), 2862 (7),
2445 (8), 2156 (7), 1576 (2), 1417 (5), 1389 (5), 1310 (4), 1024 (5), 964 (2),
832 (2), 634 cmꢀ1 (3); 1H NMR ([D6]DMSO, 400 MHz, 258C): d=
8.49 ppm (N-CHO); 13C NMR ([D6]DMSO, 101 MHz, 258C): d=172.9
(N-CHO), 123.4 ppm (N-CN); 14N NMR ([D6]DMSO, 28.9 MHz, 258C):
d=ꢀ190 (N-CN), ꢀ245 ppm (N-CHO); elemental analysis: calcd (%) for
C12H20N4O (236.32): C 60.99, H 8.53, N 23.71; found: C 60.34, H 8.27,
N 23.42.
HMIM+ncaꢀ: Potassium nitrocyanoamide (1.26 g; 10.1 mmol) was added
to a solution of 1-n-hexyl-3-methylimidazolium tetrafluoroborate (2.51 g;
9.88 mmol) in dried methanol (50 mL) at RT. After stirring for 20 h at
RT, the reaction mixture was filtered. Removal of the solvent in vaccum,
followed by a specific drying procedure (see Scheme 6) and drying for
7 d in vacuum (10ꢀ3 Torr), yielded a colorless ionic liquid (2.40 g; 96%).
M.p.: ꢀ388C; Tdec,onset =2398C; IR (ATR, 258C): n˜ =3148 (w), 3108 (w),
2956 (m), 2931 (m), 2860 (w), 2168 (s), 1571 (w), 1424 (s), 1259 (vs), 1165
(m), 951 (w), 845 (w), 760 (w), 622 cmꢀ1 (w); Raman (200 mW, 258C):
n˜ =2962 (8), 2941 (7), 2520 (5), 2171 (10), 1569 (1), 1417 (4), 1341 (2),
1261 (1), 1151 (3), 1025 (3), 955 (4), 764 cmꢀ1 (6); 13C NMR ([D6]DMSO,
101 MHz, 258C): d=116.7 ppm (N-CN); 14N NMR ([D6]DMSO,
28.9 MHz, 258C): d=ꢀ2 (N-NO2), ꢀ165 (N-NO2), ꢀ178 ppm (N-CN); el-
BMIM+fcaꢀ: Potassium formylcyanoamide (1.07 g; 9.89 mmol) was
added to a solution of 1-n-butyl-3-methylimidazolium tetrafluoroborate
(2.13 g; 9.42 mmol) in dried methanol (50 mL) at RT. After stirring for
20 h at RT, the reaction mixture was filtered. Removal of the solvent in
vaccum, followed by a specific drying procedure (see Scheme 6) and
drying for 7 d in vacuum (10ꢀ3 Torr), yielded a colorless glass (1.84 g;
94%). M.p.: 328C; Tdec,onset =2278C; IR (ATR, 258C): n˜ =3143 (m), 3074
(s), 2960 (s), 2936 (s), 2873 (m), 2150 (s), 1571 (vs), 1463 (m), 1381 (w),
1305 (s), 1167 (s), 1066 (w), 960 (w), 831 (m), 753 (m), 652 (m), 621 cmꢀ1
(m); Raman (200 mW, 258C): n˜ =3125 (2), 3081 (3), 2953 (9), 2908 (8),
2867 (6), 2145 (2), 1566 (2), 1455 (4), 1416 (10), 1375 (4), 1333 (4), 1302
(2), 1136 (2), 1092 (3), 1052 (3), 1016 (5), 887 (2), 837 (2), 701 (3),
604 cmꢀ1 (3); 1H NMR ([D6]DMSO, 400 MHz, 258C): d=8.49 ppm (N-
Chem. Asian J. 2009, 4, 1588 – 1603
ꢂ 2009 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
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A. Schulz et al.
FULL PAPERS
emental analysis: calcd (%) for C11H19N5O2 (253.31): C 52.16, H 7.56,
N 27.65; found; C 51.89, H 7.21, N 27.18.
Schnick, Inorg. Chem. 2000, 39, 665–670; e) E. Irran, B. Jꢁrgens, W.
Schnick, Chem. Eur. J. 2001, 7, 5372–5381.
HMIM+dcaꢀ: Potassium dicyanoamide (0.95 g; 9.04 mmol) was added to
a solution of 1-n-hexyl-3-methylimidazolium tetrafluoroborate (2.25 g;
8.86 mmol) in of dried methanol (50 mL) at RT. After stirring for 20 h at
RT, the reaction mixture was filtered. Removal of the solvent in vaccum,
followed by a specific drying procedure (see Scheme 6) and drying for
7 d in vacuum (10ꢀ3 Torr), yielded a colorless ionic liquid (2.03 g; 98%).
M.p.: ꢀ488C; Tdec,onset =2468C; IR (ATR, 258C): n˜ =3100 (w), 2956 (w),
2931 (w), 2860 (w), 2228 (s), 2192 (s), 2125 (vs), 1572 (m), 1466 (w), 1305
(m), 1166 (m), 753 (w), 651 (w), 622 cmꢀ1 (w); Raman (200 mW, 258C):
n˜ =3090 (1), 2958 (6), 2935 (5), 2873 (4), 2192 (10), 2135 (1), 1570 (1),
1441 (2), 1418 (3), 1387 (1), 1340 (1), 1311 (1), 1115 (1), 1023 (3), 896 (1),
665 cmꢀ1 (2); 13C NMR ([D6]DMSO, 101 MHz, 258C): d=118.9 ppm (N-
CN); 14N NMR ([D6]DMSO, 28.9 MHz, 258C): d=ꢀ229 (N-CN),
ꢀ368 ppm (N-CN); elemental analysis: calcd (%) for C12H19N5 (233.32):
C 61.77, H 8.21, N 30.02; found: C 61.46, H 7.93, N 29.69.
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Computational Details
Our goal was to compare the structures and energetics of different iso-
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Received: May 19, 2009
Published online: September 8, 2009
Chem. Asian J. 2009, 4, 1588 – 1603
ꢂ 2009 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.chemasianj.org
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